Jérôme Orivel - Publications

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Articles in international journals

P-107. Mayer VE, Lauth J, Voglmayr H & Orivel J. 2017. Convergent structure and function of mycelial galleries in two unrelated Neotropical plant-ants. Insectes Sociaux, DOI 10.1007/s00040-017-0554-y.

Abstract

The construction process and use of galleries by Azteca brevis (Myrmicinae : Dolichoderinae) inhabiting Tetrathylacium macrophyllum (Salicaceae) were compared with Allomerus decemarticulatus (Myrmicinae : Solenopsidini) galleries on Hirtella physophora (Chrysobalanaceae). Though the two ant species are phylogenetically distant, the gallery structure seems to be surprisingly similar and structurally convergent : both are pierced with numerous holes and both ant species use Chaetothyrialean fungi to strengthen the gallery walls. Al. decemarticulatus is known to use the galleries for prey capture and whether this is also the case for Az. brevis was tested in field experiments. We placed Atta workers as potential prey/threat on the galleries and recorded the behaviour of both ant species. We found considerable behavioural differences between them : Al. decemarticulatus was quicker and more efficient at capture than was Az. brevis. While most Atta workers were captured after the first 5 min by Al. decemarticulatus, significantly fewer were captured by Az. brevis even after 20 min. Moreover, the captured Atta were sometimes simply discarded and not taken to the nest by Az. brevis. As a consequence, the major function of the galleries built by Az. brevis may, therefore, be defense against intruders in contrast to Al. decemarticulatus which uses them mainly for prey capture. This may be due to a higher need for protein in Al. decemarticulatus compared to coccid-raising Az. brevis.

P-106. Aili S, Touchard A, Petitclerc F, Dejean A, Orivel J, Padula M, Escoubas P, Nicholson G. 2017. Combined peptidomic and proteomic analysis of electrically stimulated and manually dissected venom from the South American bullet ant Paraponera clavata. Journal of Proteome Research, DOI : 10.1021/acs.jproteome.6b00948

Abstract

Ants have evolved venoms rich in peptides and proteins used for predation, defense, and communication. However, they remain extremely understudied due to the minimal amount of venom secreted by each ant. The present study investigated the differences in the proteome and peptidome of the venom from the bullet ant, Paraponera clavata. Venom samples were collected from a single colony either by manual venom gland dissection or by electrical stimulation and were compared using proteomic methods. Venom proteins were separated by 2D-PAGE and identified by nanoLC-ESI-QTOF MS/ MS. Venom peptides were initially separated using C18 reversed-phase high-performance liquid chromatography, then analyzed by MALDI-TOF MS. The proteomic analysis revealed numerous proteins that could be assigned a biological function (total 94), mainly as toxins, or roles in cell regulation and transport. This investigation found that ca. 73% of the proteins were common to venoms collected by the two methods. The peptidomic analysis revealed a large number of peptides (total 309) but with <20% shared by the two collection methods. There was also a marked difference between venoms obtained by venom gland dissection from different ant colonies. These findings demonstrate the rich composition and variability of P. clavata venom.

P-105. Orivel J, Malé, P-J G, Lauth J, Roux O, Petitclerc F, Dejean A, Leroy C. 2017. Trade-offs in mutualistic investment in a tripartite symbiosis. Proceedings of the Royal Society B, 284 : 20161679.

Abstract

Species engaged in multiple, simultaneous mutualisms are subject to trade- offs in their mutualistic investment if the traits involved in each interaction are overlapping, which can lead to conflicts and affect the longevity of these associations. We investigate this issue via a tripartite mutualism involving an ant plant, two competing ant species and a fungus the ants cultivate to build galleries under the stems of their host plant to capture insect prey. The use of the galleries represents an innovative prey capture strategy compared with the more typical strategy of foraging on leaves. However, because of a limited worker force in their colonies, the prey capture behaviour of the ants results in a trade-off between plant protection (i.e. the ants patrol the foliage and attack intruders including herbivores) and ambushing prey in the galleries, which has a cascading effect on the fitness of all of the partners. The quantification of partners’ traits and effects showed that the two ant species differed in their mutualistic investment. Less investment in the galleries (i.e. in fungal cultivation) translated into more benefits for the plant in terms of less herbivory and higher growth rates and vice versa. However, the greater vegetative growth of the plants did not produce a positive fitness effect for the better mutualistic ant species in terms of colony size and production of sexuals nor was the mutualist compensated by the wider dispersal of its queens. As a consequence, although the better ant mutualist is the one that provides more benefits to its host plant, its lower host–plant exploitation does not give this ant species a competitive advantage. The local coexistence of the ant species is thus fleeting and should eventually lead to the exclusion of the less competitive species.

P-104. Salas-Lopez A, Houadria M, Menzel F, Orivel J. 2017. Ant-mediated ecosystem processes are driven by trophic community structure but mainly by the environment. Oecologia, 183 : 249-261.

Abstract

The diversity and functional identity of organisms are known to be relevant to the maintenance of ecosystem processes but can be variable in different environments. Particularly, it is uncertain whether ecosystem processes are driven by complementary effects or by dominant groups of species. We investigated how community structure (i.e., the diversity and relative abundance of biological entities) explains the community-level contribution of Neotropical ant communities to different ecosystem processes in different environments. Ants were attracted with food resources representing six ant-mediated ecosystem processes in four environments : ground and vegetation strata in cropland and forest habitats. The exploitation frequencies of the baits were used to calculate the taxonomic and trophic structures of ant communities and their contribution to ecosystem processes considered individually or in combination (i.e., multifunctionality). We then investigated whether community structure variables could predict ecosystem processes and whether such relationships were affected by the environment. We found that forests presented a greater biodiversity and trophic complementarity and lower dominance than croplands, but this did not affect ecosystem processes. In contrast, trophic complementarity was greater on the ground than on vegetation and was followed by greater resource exploitation levels. Although ant participation in ecosystem processes can be predicted by means of trophic-based indices, we found that variations in community structure and performance in ecosystem processes were best explained by environment. We conclude that determining the extent to which the dominance and complementarity of communities affect ecosystem processes in different environments requires a better understanding of resource availability to different species.

P-103. Dejean A, Azémar F, Libert M, Compin A, Hérault B, Orivel J, Bouyer T, Corbara B. 2017. Ant-lepidopteran associations along African forest edges. The Science of Nature, 104 : 7.

Abstract

Working along forest edges, we aimed to determine how some caterpillars can co-exist with territorially dominant arboreal ants (TDAAs) in tropical Africa. We recorded caterpillars from 22 lepidopteran species living in the presence of five TDAA species. Among the defoliator and/or nectarivorous caterpillars that live on tree foliage, the Pyralidae and Nymphalidae use their silk to protect them- selves from ant attacks. The Notodontidae and lycaenid Polyommatinae and Theclinae live in direct contact with ants ; the Theclinae even reward ants with abundant secretions from their Newcomer gland. Lichen feeders (lycaenid ; Poritiinae), protected by long bristles, also live among ants. Some lycaenid Miletinae caterpillars feed on ant-attended membracids, including in the shelters where the ants attend them ; Lachnocnema caterpillars use their forelegs to obtain trophallaxis from their host ants. Caterpillars from other species live inside weaver ant nests. Those of the genus Euliphyra (Miletinae) feed on ant prey and brood and can obtain trophallaxis, while those from an Eberidae species only prey on host ant eggs. Eublemma albifascia (Erebidae) caterpillars use their thoracic legs to obtain trophallaxis and trophic eggs from ants. Through transfer bioassays of last instars, we noted that herbivorous caterpillars living in contact with ants were always accepted by alien conspecific ants ; this is likely due to an intrinsic appeasing odor. Yet, caterpillars living in ant shelters or ant nests probably acquire cues from their host colonies because they were considered aliens and killed. We conclude that co-evolution with ants occurred similarly in the Heterocera and Rhopalocera.

P-102. Leroy C, Petitclerc F, Orivel J, Corbara B, Carrias JF, Dejean A, Céréghino, R. 2017. The influence of light, substrate and seed origin on the germination and establishment of an ant-garden bromeliad. Plant Biology, 19 : 70-78.

Abstract

Plant germination and development depend upon a seed’s successful dispersal into a suitable habitat and its ability to grow and survive within the surrounding biotic and abiotic environment. The seeds of Aechmea mertensii, a tank-bromeliad species, are dispersed by either Camponotus femoratus or Neoponera goeldii, two ant species that initiate ant gardens (AGs). These two mutualistic ant species influence the vegetative and reproductive traits of the bromeliad through their divergent ecological preferences (i.e. light and substrate). We hypothesised that the seeds dispersed by these two ant species have underlying genetic differences affecting germination, growth and survival of A. mertensii seedlings in different ways. To test this, we used an experimental approach consisting of sowing seeds of A. mertensii : (i) taken from the two AG–ant associations (i.e. seed origin), (ii) in two contrasting light conditions, and (iii) on three different substrates. Light and substrate had significant effects on germination, survival and on eight key leaf traits reflecting plant performance. Seed origin had a significant effect only on germination and on two leaf traits (total dry mass and relative growth rate). Overall, this bromeliad performs better (i.e. high growth and survival rates) when growing both in the shade and in the carton nest developed by C. femoratus ants. These results suggest that the plasticity of the tank bromeliad A. mertensii is mainly due to environment but also to genetic differences related to seed origin, as some traits are heritable. Thus, these two ant species may play contrasting roles in shaping plant evolution and speciation.

P-101. Malé PJG, Leroy C, Humblot P, Dejean A, Quilichini A & Orivel J. 2016. Limited gene dispersal and spatial genetic structure as stabilizing factors in an ant-plant mutualism. Journal of Evolutionary Biology, 29 : 2519-2529.

Abstract

Comparative studies of the population genetics of closely associated species are necessary to properly understand the evolution of these relationships because gene flow between populations affects the partners’ evolutionary potential at the local scale. As a consequence (at least for antagonistic interactions), asymmetries in the strength of the genetic structures of the partner populations can result in one partner having a co-evolutionary advantage. Here, we assess the population genetic structure of partners engaged in a species-specific and obligatory mutualism : the Neotropical ant-plant, Hirtella physophora, and its ant associate, Allomerus decemarticulatus. Although the ant cannot complete its life cycle elsewhere than on H. physophora and the plant cannot live for long without the protection provided by A. decemarticulatus, these species also have antagonistic interactions : the ants have been shown to benefit from castrating their host plant and the plant is able to retaliate against too virulent ant colonies. We found similar short dispersal distances for both partners, resulting in the local transmission of the association and, thus, inbred populations in which too virulent castrating ants face the risk of local extinction due to the absence of H. physophora offspring. On the other hand, we show that the plant populations probably experienced greater gene flow than did the ant populations, thus enhancing the evolutionary potential of the plants. We conclude that such levels of spatial structure in the partners’ populations can increase the stability of the mutualistic relationship. Indeed, the local transmission of the association enables partial alignments of the partners’ interests, and population connectivity allows the plant retaliation mechanisms to be locally adapted to the castration behaviour of their symbionts.

P-100. Touchard A, Brust A, Cardoso FC, Chin YK, HerzigV, Jin AH, Dejean A, Alewood PF, King GF, Orivel J, Escoubas P. 2016. Isolation and characterization of a structurally unique β-hairpin venom peptide from the predatory ant Anochetus emarginatus. Biochimica et Biophysica Acta, 1860 : 2553-2562.

Abstract

Background : Most ant venoms consist predominantly of small linear peptides, although some contain disulfide-linked peptides as minor components. However, in striking contrast to other ant species, some Anochetus venoms are composed primarily of disulfide-rich peptides. In this study, we investigated the venom of the ant Anochetus emarginatus with the aim of exploring these novel disulfide-rich peptides.
Methods : The venom peptidome was initially investigated using a combination of reversed-phase HPLC and mass spectrometry, then the amino acid sequences of the major peptides were determined using a combination of Edman degradation and de novo MS/MS sequencing. We focused on one of these peptides, U1-PONTX-Ae1a (Ae1a), because of its novel sequence, which we predicted would form a novel 3D fold. Ae1a was chemically synthesized using Fmoc chemistry and its 3D structure was elucidated using NMR spectroscopy. The peptide was then tested for insecticidal activity and its effect on a range of human ion channels.
Results : Seven peptides named poneritoxins (PONTXs) were isolated and sequenced. The three-dimensional structure of synthetic Ae1a revealed a novel, compact scaffold in which a C-terminal β-hairpin is connected to the N-terminal region via two disulfide bonds. Synthetic Ae1a reversibly paralyzed blowflies and inhibited human L-type voltage-gated calcium channels (CaV1).
Conclusions : Poneritoxins from Anochetus emarginatus venom are a novel class of toxins that are structurally unique among animal venoms.
General significance : This study demonstrates that Anochetus ant venoms are a rich source of novel ion channel modulating peptides, some of which might be useful leads for the development of biopesticides.

P-99. Aili S, Touchard A, Koh J, Dejean A, Orivel J, Padula M, Escoubas P, Nicholson G. 2016. Comparisons of protein and peptide complexity in poneroid and formicoid ant venoms. Journal of Proteome Research, 15 : 3039-3054.

Abstract Animal venom (...)

Abstract
Animal venom peptides are currently being developed as novel drugs and bioinsecticides. Because ants use venoms for defense and predation, venomous ants represent an untapped source of potential bioactive toxins. This study compared the protein and peptide components of the poneroid ants Neoponera commutata, Neoponera apicalis, and Odontomachus hastatus and the formicoid ants Ectatomma
tuberculatum
, Ectatomma brunneum, and Myrmecia gulosa. 1D and 2D PAGE revealed venom proteins in the mass range <10 to >250 kDa. NanoLC-ESI-QTOF MS/MS analysis of tryptic peptides revealed the presence of common venom proteins and also many undescribed proteins. RP-HPLC separation followed by MALDI-TOF MS of the venom peptides also revealed considerable heterogeneity. It was found that the venoms contained between 144 and 1032 peptides with 5−95% of peptides in the ranges 1−4 and 1−8 kDa for poneroid and formicoid ants, respectively. By employing the reducing MALDI matrix 1,5-diaminonapthalene, up to 28 disulfide-bonded peptides were also identified in each of the venoms. In particular, the mass range of peptides from poneroid ants is lower than peptides from other venoms, indicating possible novel structures and pharmacologies. These results indicate that ant venoms represent an enormous, untapped source of novel therapeutic and bioinsecticide leads.

P-98. Dejean A, Orivel J, Azémar F, Hérault B & CorbaraB. 2016. A cuckoo-like parasitic moth leads African weaver ant colonies to their ruin. Scientific Reports, 6 : 23778.

Abstract

In myrmecophilous Lepidoptera, mostly lycaenids and riodinids, caterpillars trick ants into transporting them to the ant nest where they feed on the brood or, in the more derived “cuckoo strategy”, trigger regurgitations (trophallaxis) from the ants and obtain trophic eggs. We show for the rst time that the caterpillars of a moth (Eublemma albifascia ; Noctuidae ; Acontiinae) also use this strategy to obtain regurgitations and trophic eggs from ants (Oecophylla longinoda). Females short-circuit the adoption process by laying eggs directly on the ant nests, and workers carry just-hatched caterpillars inside. Parasitized colonies sheltered 44 to 359 caterpillars, each receiving more trophallaxis and trophic eggs than control queens. The thus-starved queens lose weight, stop laying eggs (which transport the pheromones that induce infertility in the workers) and die. Consequently, the workers lay male-destined eggs before and after the queen’s death, allowing the colony to invest its remaining resources in male production before it vanishes.

P-97. Touchard A, Aili SR, Fox EGP, Escoubas P, Orivel J, Nicholson GM, Dejean A. 2016. The biochemical toxin arsenal from ant venoms. Toxins, 8 : 30.

Abstract

Ants (Formicidae) represent a taxonomically diverse group of hymenopterans with over 13,000 extant species, the majority of which inject or spray secretions from a venom gland. The evolutionary success of ants is mostly due to their unique eusociality that has permitted them to develop complex collaborative strategies, partly involving their venom secretions, to defend their nest against predators, microbial pathogens, ant competitors, and to hunt prey. Activities of ant venom include paralytic, cytolytic, haemolytic, allergenic, pro-inflammatory, insecticidal, antimicrobial, and pain-producing pharmacologic activities, while non-toxic functions include roles in chemical communication involving trail and sex pheromones, deterrents, and aggregators. While these diverse activities in ant venoms have until now been largely understudied due to the small venom yield from ants, modern analytical and venomic techniques are beginning to reveal the diversity of toxin structure and function. As such, ant venoms are distinct from other venomous animals, not only rich in linear, dimeric and disulfide-bonded peptides and bioactive proteins, but also other volatile and non-volatile compounds such as alkaloids and hydrocarbons. The present review details the unique structures and pharmacologies of known ant venom proteinaceous and alkaloidal toxins and their potential as a source of novel bioinsecticides and therapeutic agents.

P-96. Dejean A, Azémar F, Céréghino R, Leponce M, Corbara B, Orivel J, Compin A. 2016. The dynamics of ant mosaics in tropical rainforests characterized using the Self-Organizing Map algorithm. Insect Science, 23 : 630-637.

Abstract

Ants, the most abundant taxa among canopy-dwelling animals in tropical rainforests, are mostly represented by territorially dominant arboreal ants (TDAs) whose territories are distributed in a mosaic pattern (arboreal ant mosaics). Large TDA colonies regulate insect herbivores, with implications for forestry and agronomy. What generates these mosaics in vegetal formations, which are dynamic, still needs to be better understood. So, from empirical research based on 3 Cameroonian tree species (Lophira alata, Ochnaceae ; Anthocleista vogelii, Gentianaceae ; and Barteria fistulosa, Passifloraceae), we used the Self-Organizing Map (SOM, neural network) to illustrate the succession of TDAs as their host trees grow and age. The SOM separated the trees by species and by size for L. alata, which can reach 60 m in height and live several centuries. An ontogenic succession of TDAs from sapling to mature trees is shown, and some ecological traits are highlighted for certain TDAs. Also, because the SOM permits the analysis of data with many zeroes with no effect of outliers on the overall scatterplot distributions, we obtained ecological information on rare species. Finally, the SOM permitted us to show that functional groups cannot be selected at the genus level as congeneric species can have very different ecological niches, something particularly true for Crematogaster spp., which include a species specifically associated with B. fistulosa, nondominant species and TDAs. Therefore, the SOM permitted the complex relationships between TDAs and their growing host trees to be analyzed, while also providing new information on the ecological traits of the ant species involved.

P-95. Houadria M, Blüthgen N, Salas-Lopez A, Schmitt MI, Arndt J, Schneider E, Orivel J & Menzel F. 2016. The relation between circadian asynchrony, functional redundancy and trophic performance in tropical ant communities. Ecology, 97 : 225-235.

Abstract

The diversity-stability relationship has been under intense scrutiny for the past decades, and temporal asynchrony is recognized as an important aspect of ecosystem stability. In contrast to relatively well-studied interannual and seasonal asynchrony, few studies investigate the role of circadian cycles for ecosystem stability. Here, we studied multifunctional redundancy of diurnal and nocturnal ant communities in four tropical rain forest sites. We analyzed how it was influenced by species richness, functional performance, and circadian asynchrony. In two neotropical sites, species richness and functional redundancy were lower at night. In contrast, these parameters did not differ in the two paleotropical sites we studied. Circadian asynchrony between species was pronounced in the neotropical sites, and increased circadian functional redundancy. In general, species richness positively affected functional redundancy, but the effect size depended on the temporal and spatial breadth of the species with highest functional performance. Our analysis shows that high levels of trophic performance were only reached through the presence of such high-performing species, but not by even contributions of multiple, less-efficient species. Thus, these species can increase current functional performance, but reduce overall functional redundancy. Our study highlights that diurnal and nocturnal ecosystem properties of the very same habitat can markedly differ in terms of species richness and functional redundancy. Consequently, like the need to study multiple ecosystem functions, multiple periods of the circadian cycle need to be assessed in order to fully understand the diversity-stability relationship in an ecosystem.

P-94. Touchard A, Dejean A, Escoubas P & Orivel J. 2015. Intraspecific variations in the venom peptidome of the ant Odontomachus haematodus (Formicidae : Ponerinae) from French Guiana. Journal of Hymenoptera Research, 47 : 87-101.

Abstract

Ant venoms are complex cocktails of toxins employed to subdue prey and to protect the colony from predators and microbial pathogens. Although the extent of ant venom peptide diversity remains largely unexplored, previous studies have revealed the presence of numerous bioactive peptides in most stinging ant venoms. We investigated the venom peptidome of the ponerine ant Odontomachus haematodus using LC-MS analysis and then verified whether the division of labor in the colonies and their geographical location are correlated with differences in venom composition. Our results reveal that O. haematodus venom is comprised of 105 small linear peptides. The venom composition does not vary between the different castes (i.e., nurses, foragers and queens), but an intraspecific variation in peptide content was observed, particularly when the colonies are separated by large distances. Geographical variation appears to increase the venom peptide repertoire of this ant species, demonstrating its intraspecific venom plasticity.

P-93. Basset Y, Cizek L, Cuénoud P, Didham RK, Novotny V, Ødegaard F, Roslin T, Tishechkin AK, Schmidl J, Winchester NN, Roubik DW, Aberlenc HP, Bail J, Barrios H, Bridle JR, Castaño- Meneses G, Corbara B, Curletti G, Duarte da Rocha W, De Bakker D, Delabie JHC, Dejean A, Fagan LL, Floren A, Kitching RL, Medianero E, Gama de Oliveira E, Orivel J, Pollet M, Rapp M, Ribeiro SP, Roisin Y, Schmidt JB, Sørensen L, Lewinsohn TM, Leponce M. 2015. Arthropod distribution in a tropical rainforest : tackling a four dimensional puzzle. PLoS One, 10 : e0144110.

Abstract

Quantifying the spatio-temporal distribution of arthropods in tropical rainforests represents a first step towards scrutinizing the global distribution of biodiversity on Earth. To date most studies have focused on narrow taxonomic groups or lack a design that allows partitioning of the components of diversity. Here, we consider an exceptionally large dataset (113,952 individuals representing 5,858 species), obtained from the San Lorenzo forest in Panama, where the phylogenetic breadth of arthropod taxa was surveyed using 14 protocols targeting the soil, litter, understory, lower and upper canopy habitats, replicated across seasons in 2003 and 2004. This dataset is used to explore the relative influence of horizontal, vertical and seasonal drivers of arthropod distribution in this forest. We considered arthropod abundance, observed and estimated species richness, additive decomposition of species richness, multiplicative partitioning of species diversity, variation in species composition, species turnover and guild structure as components of diversity. At the scale of our study (2km of distance, 40m in height and 400 days), the effects related to the vertical and seasonal dimensions were most important. Most adult arthropods were collected from the soil/ litter or the upper canopy and species richness was highest in the canopy. We compared the distribution of arthropods and trees within our study system. Effects related to the seasonal dimension were stronger for arthropods than for trees. We conclude that : (1) models of beta diversity developed for tropical trees are unlikely to be applicable to tropical arthropods ; (2) it is imperative that estimates of global biodiversity derived from mass collecting of arthropods in tropical rainforests embrace the strong vertical and seasonal partitioning observed here ; and (3) given the high species turnover observed between seasons, global climate change may have severe consequences for rainforest arthropods.

P-92. Vedel V, Cerdan A, Martinez Q, Baraloto C, Petitclerc F, Orivel J & Fortunel C. 2015. Sampling daytime does not affect estimates of spider diversity across a land use gradient in the Neotropics. Journal of Arachnology, 43 : 413-416.

Abstract

To obtain a reliable description of spider communities, robust sampling protocols are crucial. However, it remains unclear if descriptions of spider communities in tropical habitats require both day and night sampling. Here we tested whether sampling both day and night in high and low vegetation strata would lead to better diversity estimates of spider communities than sampling at only one period of the day. We determined spider taxonomic diversity in a network of 12 plots in French Guiana along a vegetation gradient. We found high alpha diversity of spiders as expected for a tropical area at every site. We showed strong differences in spider alpha and beta diversity between high and low vegetation strata, while they were similar between day and night sampling. Our results suggest that collecting spiders at only one period is sufficient to describe the diversity of spider communities across land use types in the neotropics.

P-91. Dejean A., Ryder S., Bolton B., Compin A., Leponce M., Azémar F., Céréghino R., Orivel, J., Corbara B. 2015. How territoriality and host-tree taxa determine the structure of ant mosaics. The Science of Nature 102 : 33.

Abstract

Very large colonies of territorially dominant arboreal ants (TDAAs), whose territories are distributed in a mosaic pattern in the canopies of many tropical rainforests and tree crop plantations, have a generally positive impact on their host trees. We studied the canopy of an old Gabonese rainforest (ca 4.25 ha sampled, corresponding to 206 "large" trees) at a stage just preceding forest maturity (the Caesalpinioideae dominated ; the Burseraceae were abundant). The tree crowns sheltered colonies from 13 TDAAs plus a co-dominant species out of the 25 ant species recorded. By mapping the TDAAs’ territories and using a null model co-occurrence analysis, we confirmed the existence of an ant mosaic. Thanks to a large sampling set and the use of the self-organizing map algorithm (SOM), we show that the distribution of the trees influences the structure of the ant mosaic, suggesting that each tree taxon attracts certain TDAA species rather than others. The SOM also improved our knowledge of the TDAAs’ ecological niches, showing that these ant species are ecologically distinct from each other based on their rela- tionships with their supporting trees. Therefore, TDAAs should not systematically be placed in the same functional group even when they belong to the same genus. We conclude by reiterating that, in addition to the role played by TDAAs’ territorial competition, host trees contribute to structuring ant mosaics through multiple factors, including host-plant selection by TDAAs, the age of the trees, the presence of extrafloral nectaries, and the taxa of the associated hemipterans.

P-90. Bertelsmeier C, Avril A, Blight O, Confais A, Diez L, Jourdan H, Orivel J, Saint Germès N & Courchamp F. 2015. Different behavioural strategies among seven highly invasive ant species. Biological Invasions, 17 : 2491-2503.

Abstract

Ants figure prominently among the worst invasive species because of their enormous ecological and economic impacts. However, it remains to be investigated which species would be behaviourally dominant when confronted with another invasive ant species, should two species be introduced in the same area. In the future, many regions might have suitable environmental conditions for several invasive ant species, as predicted under climate change scenarios. Here, we explored interactions among several highly invasive ant species, which have been shown to have overlapping suitable areas. The aim of this study was to evaluate the performance in interference competition of seven of the world’s worst invasive ant species (Anoplolepis gracilipes, Paratrechina longicornis, Myrmica rubra, Linepithema humile, Lasius neglectus, Wasmannia auropunctata and Pheidole megacephala). We conducted pairwise confrontations, testing the behaviour of each species against each of the six other species (in total 21 dyadic confronta- tions). We used single worker confrontations and group interactions of 10 versus 10 individuals to establish a dominance hierarchy among these invasive ant species. We discovered two different behavioural strategies among these invasive ants : three species displayed evasive or indifferent behaviour when individuals or groups were confronted (A. gracilipes, Pa. longicornis, M. rubra), while the four remaining species were highly aggressive during encounters and formed a linear dominance hierarchy. These findings contrast with the widespread view that invasive ants form a homogeneous group of species displaying the ‘invasive syndrome’, which includes generally aggressive behaviour. The dominance hierarchy among the four aggressive species may be used to predict the outcome of future competitive interactions under some circumstances. Yet, the existence of several behavioural strategies renders such a prediction less straightforward.

P-89. Touchard A, Koh JMS, Aili SR, Dejean A, Nicholson GM, Orivel J, Escoubas P. 2015. The complexity and structural diversity of ant venom peptidomes is revealed by mass spectrometry profiling. Rapid Communications in Mass Spectrometry, 29 : 385-396.

Abstract

RATIONALE : Compared with other animal venoms, ant venoms remain little explored. Ants have evolved complex venoms to rapidly immobilize arthropod prey and to protect their colonies from predators and pathogens. Many ants have retained peptide-rich venoms that are similar to those of other arthropod groups.
METHODS : With the goal of conducting a broad and comprehensive survey of ant venom peptide diversity, we investigated the peptide composition of venoms from 82 stinging ant species from nine subfamilies using matrix- assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS). We also conducted an in-depth investigation of eight venoms using reversed-phase high-performance liquid chromatography (RP-HPLC) separation coupled with offline MALDI-TOFMS.
RESULTS : Our results reveal that the peptide compositions of ant venom peptidomes from both poneroid and formicoid ant clades comprise hundreds of small peptides (<4 kDa), while large peptides (>4 kDa) are also present in the venom of formicoids. Chemical reduction revealed the presence of disulfide-linked peptides in most ant subfamilies, including peptides structured by one, two or three disulfide bonds as well as dimeric peptides reticulated by three disulfide bonds.
CONCLUSIONS : The biochemical complexity of ant venoms, associated with an enormous ecological and taxonomic diversity, suggests that stinging ant venoms constitute a promising source of bioactive molecules that could be exploited in the search for novel drug and biopesticide leads.

P-88. Houadria M, Salas-Lopez A, Orivel J, Blüthgen N & Menzel F. 2015. Dietary and temporal niche differentiation in species-rich assemblages - can they explain local tropical ant coexistence ? Biotropica, 47 : 208-217.

Abstract

How species with similar ecological requirements avoid competitive exclusion remains contentious, especially in the species-rich tropics. Niche differentiation has been proposed as a major mechanism for species coexistence. However, different niche dimensions must be studied simultaneously to assess their combined effects on diversity and composition of a community. In most terrestrial ecosystems, ants are among the most abundant and ubiquitous animals. Since they display direct, aggressive competition and often competitively dis- place subordinate species from resources, niche differentiation may be especially relevant among ants. We studied temporal and trophic niche differentiation in a ground ant community in a forest fragment in French Guiana. Different baits were presented during day and night to assess the temporal and dietary niches of the local species. They represented natural food resources such as sugars, carrion, excrements, seeds, and live prey. In addition, pitfalls provided a background measure of ant diversity. The communities attracted to the different baits significantly differed from each other, and even less attractive baits yielded additional species. We detected species special- ized on living grasshoppers, sucrose, seeds, or dead insects. Community-level differences between day and night were larger than those between baits, and many species were temporally specialized. In contrast to commonness, foraging efficiency of species was correlated to food specialization. We conclude that many ant species occupy different temporal or dietary niches. However, for many generalized species, the dietary, and temporal niche differentiation brought forward through our sampling effort, cannot alone explain their coexistence.

P-87. Robillard T, ter Hofstede H, Orivel J & Vicente NM. 2015. Bioacoustics of the Neotropical Eneopterinae (Orthoptera, Grylloidea, Gryllidae). Bioacoustics, 24 : 123-143.

Abstract

In members of the cricket subfamily Eneopterinae (Orthoptera, Grylloidea), songs with powerful high-frequency (HF) harmonics have evolved, which likely represents a distinctive acoustic adaptation. In this study, we analysed or reanalysed the songs of the three eneopterine genera present in the Neotropics to evaluate whether they also possess high-amplitude HF components. We present new data and combine several lines of evidence to interpret or reinterpret the calling signals of a representative species for each genus. We used new recordings in order to detect and analyse potential HF components of the songs. Stridulatory files were measured, and stridulation was studied using high-speed video recordings. The results suggest that all eneopterine genera from the Neotropics use HFs to communicate, based on the rich harmonic content of their songs. Strikingly, the Neotropical eneopterines possess high dominant frequencies, recalling the patterns observed in the tribe Lebinthini, the most speciose tribe of the subfamily distributed in the Western Pacific region and in Southeast Asia : Ligypterus and Ponca show dominant harmonic peaks, whereas Eneoptera possesses unique features. The three species under study, however, deal differently with HFs.

P-86. Malé PJG, Leroy C, Lusignan L, Petitclerc F, Quilichini A, Orivel J. 2015. The reproductive biology of the myrmecophyte, Hirtella physophora, and the limitation of negative interactions between pollinators and ants. Arthropod-Plant Interactions, 9 : 23-31.

Abstract

Myrmecophytism occurs in plants that offer ants a nesting space and, often, food rewards in exchange for protection from predators and competitors. Such biotic protection by ants can, however, interfere with the activity of pollinators leading to potential negative consequences for the plant’s reproduction. In this study, we focused on the association between the understory myrmecophyte, Hirtella physophora (Chrysobalanaceae), and its obligate ant partner, Allomerus decemarticulatus (Myrmicinae). We investigated the reproductive biology of H. physophora and the putative mechanisms that may limit ant–pollinator conflict. Our results show that H. physophora is an obligate outcrosser, self-incompatible, and potentially insect-pollinated species. The reproduction of H. physophora relies entirely on pollen transfer by pollinators that are likely quite specific. Potential interference between flower-visiting insects during pollination may also be lessened by a spatial and temporal segregation of ant and pollinator activities, thus enabling pollen transfer and fruit production.

P-85. Gao H, Grüschow S, Barke J, Seipke RF, Hill LM, Orivel J, Yu DW, Hutchings M & Goss RJM. 2014. Filipins : the first antifungal “weed killers” identified from bacteria isolated from the trap-ant. RCS Advances, 4:57267-57270.

Abstract

Allomerus ants ensure that they have sufficient nitrogen in their diet by trapping and consuming other insects. In order to construct their traps, like the more extensively studied leaf cutter ants, they employ fungal farming. Pest management within these fungal cultures has been speculated to be due to the ants’ usage of actinomycetes capable of producing antifungal compounds, analogous to the leafcutter ant mutualism. Here we report the first identification of a series of antifungal compounds, the filipins, and their associated biosynthetic genes isolated from a bacterium associated with this system.

P-84. Aili SR, Touchard A, Escoubas P, Padula M, Orivel J, Dejean A, Nicholson GM. 2014. Diversity of peptide toxins in stinging ant venoms. Toxicon, 92:166-178.

Abstract

Ants (Hymenoptera : Formicidae) represent a taxonomically diverse group of arthropods comprising nearly 13,000 extant species. Sixteen ant subfamilies have individuals that possess a stinger and use their venom for purposes such as a defence against predators, competitors and microbial pathogens, for predation, as well as for social communication. They exhibit a range of activities including antimicrobial, haemolytic, cytolytic, paralytic, insecticidal and pain-producing pharmacologies. While ant venoms are known to be rich in alkaloids and hydrocarbons, ant venoms rich in peptides are becoming more common, yet remain understudied. Recent advances in mass spectrometry techniques have begun to reveal the true complexity of ant venom peptide composition. In the few venoms explored thus far, most peptide toxins appear to occur as small polycationic linear toxins, with antibacterial properties and insecticidal activity. Unlike other venomous animals, a number of ant venoms also contain a range of homodimeric and heterodimeric peptides with one or two interchain disulfide bonds possessing pore-forming, allergenic and paralytic actions. However, ant venoms seem to have only a small number of monomeric disulfide-linked peptides. The present review details the structure and pharmacology of known ant venom peptide toxins and their potential as a source of novel bioinsecticides and therapeutic agents.

P-83. Touchard A, Labrière N, Roux O, Petitclerc F, Orivel J, Escoubas P, Koh JMS, Nicholson GM & Dejean A. 2014. Venom toxicity and composition in three Pseudomyrmex ant species having different nesting modes. Toxicon, 88:67-76.

Abstract

We aimed to determine whether the nesting habits of ants have influenced their venom toxicity and composition. We focused on the genus Pseudomyrmex (Pseudomyrmecinae) comprising terrestrial and arboreal species, and, among the latter, plant-ants that are obligate inhabitants of myrmecophytes (i.e., plants sheltering ants in hollow structures). Contrary to our hypothesis, the venom of the ground-dwelling species, Pseudomyrmex termitarius, was as efficacious in paralyzing prey as the venoms of the arboreal and the plant-ant species, Pseudomyrmex penetrator and Pseudomyrmex gracilis. The lethal potency of P. termitarius venom was equipotent with that of P. gracilis whereas the venom of P. penetrator was less potent. The MALDI-TOF MS analysis of each HPLC fraction of the venoms showed that P. termitarius venom is composed of 87 linear peptides, while both P. gracilis and P. penetrator venoms (23 and 26 peptides, respectively) possess peptides with disulfide bonds. Furthermore, P. penetrator venom contains three hetero- and homodimeric peptides consisting of two short peptidic chains linked together by two interchain disulfide bonds. The large number of peptides in P. termitarius venom is likely related to the large diversity of potential prey plus the antibacterial peptides required for nesting in the ground. Whereas predation involves only the prey and predator, P. penetrator venom has evolved in an environment where trees, defoliating insects, browsing mammals and ants live in equilibrium, likely explaining the diversity of the peptide structures.

P-82. Touchard A, Dauvois M, Arguel MJ, Petitclerc F, Leblanc M, Dejean A, Orivel J, Nicholson GM & Escoubas P. 2014. Elucidation of the unexplored biodiversity of ant venom peptidomes via MALDI-TOF mass spectrometry and its application for chemotaxonomy. Journal of Proteomics, 105:217-31

Abstract

The rise of integrative taxonomy, a multi-criteria approach used in characterizing species, fosters the development of new tools facilitating species delimitation. Mass spectrometric (MS) analysis of venom peptides from venomous animals has previously been demonstrated to be a valid method for identifying species. Here we aimed to develop a rapid chemotaxonomic tool for identifying ants based on venom peptide mass fingerprinting. The study focused on the biodiversity of ponerine ants (Hymenoptera : Formicidae : Ponerinae) in French Guiana. Initial experiments optimized the use of automated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDITOF MS) to determine variations in the mass profiles of ant venoms using several MALDI matrices and additives. Data were then analyzed via a hierarchical cluster analysis to classify the venoms of 17 ant species. In addition, phylogenetic relationships were assessed and were highly correlated with methods using DNA sequencing of the mitochondrial gene cytochrome c oxidase subunit 1. By combining a molecular genetics approach with this chemotaxonomic approach, we were able to improve the accuracy of the taxonomic findings to reveal cryptic ant species within species complexes. This chemotaxonomic tool can therefore contribute to more rapid species identification and more accurate taxonomies.

P-81. Menzel F, Orivel J, Kaltenpoth M & Schmitt T. 2014. What makes you a potential partner ? Insights from convergently evolved ant-ant symbioses. Chemoecology, 24:105-119

Abstract

Mutualistic, commensalistic or parasitic interactions are unevenly distributed across the animals and plants : in certain taxa, such interspecific associations evolved more often than in others. Within the ants, associations between species of the genera Camponotus and Crematogaster evolved repeatedly and include trail-sharing associations, where two species share foraging trails, and parabioses, where two species share a nest without aggression. Camponotus and Crematogaster may possess life-history traits that favour the evolution of associations. To identify which traits are affected by the association, we investigated a neotropical parabiosis of Ca. femoratus and Cr. levior and compared it to a paleotropical parabiosis and a trail-sharing association. The two neotropical species showed altered cuticular hydrocarbon profiles compared to non-parabiotic species accompanied by low levels of interspecific aggression. Both species occurred in two chemically distinct types. Camponotus followed artificial trails of Crematogaster pheromones, but not vice versa. The above traits were also found in the paleotropical parabiosis, and the trail-following results match those of the trail-sharing association. In contrast to paleotropical parabioses, however, Camponotus was dominant, had a high foraging activity and often fought against Crematogaster over food resources. We suggest three potential preadaptations for parabiosis. First, Crematogaster uses molecules as trail pheromones, which can be perceived by Camponotus, too. Second, nests of Camponotus are an important benefit to Crematogaster and may create a selection pressure for the latter to tolerate Camponotus. Third, there are parallel, but unusual, shifts in cuticular hydrocarbon profiles between neotropics and paleotropics, and between Camponotus and Crematogaster.

P-80. Malé PJG, Ferdy JB, Leroy C, Roux O, Lauth J, Avilez A, Dejean A, Quilichini A & Orivel J. 2014. Retaliation in response to castration promotes a low level of virulence in an ant-plant mutualism. Evolutionary Biology, 41:22-28.

Abstract

The diversion of a host’s energy by a symbiont for its own benefit is a major source of instability in hor- izontally-transmitted mutualisms. This instability can be counter-balanced by the host’s retaliation against exploiters. Such responses are crucial to the maintenance of the relationship. We focus on this issue in an obligate ant–plant mutualism in which the ants are known to partially castrate their host plant. We studied plant responses to various levels of castration in terms of (1) global vegetative investment and (2) investment in myrmecophytic traits. Castration led to a higher plant growth rate, signalling a novel case of gigantism induced by parasitic castration. On the other hand, completely castrated plants produced smaller nesting and food resources (i.e. leaf pouches and extra floral nectaries). Since the number of worker larvae is correlated to the volume of the leaf pouches, such a decrease in the investment in myrmecophytic traits demonstrates for the first time the existence of inducible retaliation mechanisms against too virulent castrating ants. Over time, this mechanism promotes an intermediate level of castration and enhances the stability of the mutualistic relationship by providing the ants with more living space while allowing the plant to reproduce.

P-79. Groc S, Delabie JHC, Fernandez, F, Leponce, M, Orivel J & Dejean A. 2014. Leaf-litter ant communities in a pristine Guianese rainforest : stable functional structure versus high species turnover. Myrmecological News, 19:43-51.

Abstract

We compared the ant assemblages from four very heterogeneous habitats over a short-distance elevational gradient of vegetation (due to the presence of an inselberg) at the Nouragues Research Station, French Guiana. We focused on litter-dwelling ants, combining the use of pitfall traps and the Winkler method according to the Ants of the Leaf Litter Protocol. This permitted us to note (1) a high leaf-litter ant diversity overall and a decreasing diversity gradient from the lowland rainforest to the top of the inselberg, and (2) differences in species density, composition and functional structure. While the ant assemblages on the plateau and inselberg can be considered functionally similar and typical of an Amazonian rainforest, that of the transition forest, relatively homogenous, rather corresponded to an ant fauna typical of open areas. By contrast, the liana forest assemblage was unexpectedly richer and denser than the others, sheltering a litter-dwelling ant fauna dominated by numerous and abundant cryptic species. These taxonomical and functional dissi- milarities may reflect the influence of the environmental heterogeneity, which, through variable abiotic conditions, can contribute to maintaining a notably rich ant biodiversity in these Neotropical habitats.

P-78. Dejean A, Corbara B, Roux O & Orivel J. 2014. The antipredatory behaviours of Neotropical ants towards army ant raids (Hymenoptera : Formicidae). Myrmecological News, 19:17-24.

Abstract

Group hunting, nomadism, wingless queens and colony fission characterize army ants, allowing them to have become the main tropical arthropod predators, mostly of other social insects. We studied the reactions of different ant species to the New World army ants Eciton burchellii (WESTWOOD, 1842) and E. hamatum (FABRICIUS, 1782) (Ecitoninae). We compiled our results with those already known in a synthetic appendix. A wide range of ant species react to the approach of army ant raids by evacuating their nests with several workers transporting brood. The Eciton plunder a large part of the brood but rarely kill workers or queens, so that the latter return to their nest and resume colony activity. One exception is Paratrechina longicornis (LATREILLE, 1802) colonies that quickly evacuate their nest, so that the entire colony can generally escape a raid. Another is Leptogenys mexicana (MAYR, 1870) that leave their nests in columns while some nestmates resist the attack ; they therefore lose only a few larvae. We noted that colonies can avoid being raided if the army ants ignore them (Atta cephalotes (LINNAEUS, 1758)), or if the workers produce a repellent substance (Azteca associated with myrmecophytic Cecropia) or are repellent themselves (Pachycondyla villosa (FABRICIUS, 1804), Ectatomma spp.). In the other cases, a part of the brood is lost. When an Eciton raid approached the base of their host-tree trunk, Azteca andreae GUERRERO, DELABIE & DEJEAN, 2010 workers dropped a part of their brood on the ground. While numerous Eciton workers were gathering up this brood, the front of the column advanced, so that the Azteca andreae nests were not plundered. Pheidole megacephala (FABRICIUS, 1793) nests were partly plundered as the workers reacted aggressively, blocking the Eciton inside their nests during a long time. When the latter returned toward their bivouac, they were attacked and killed by their nestmates whether or not they had retrieved Pheidole brood. Consequently, the front of the column turned away from the Pheidole nest.

P-77. Dejean A, Orivel J, Rossi V, Roux O, Lauth J, Malé PJG, Céréghino R & Leroy C. 2013. Predation success by a plant-ant indirectly favours the growth and fitness of its host myrmecophyte. PLoS ONE, 8 : e59405.

Abstract

Mutualisms, or interactions between species that lead to net fitness benefits for each species involved, are stable and ubiquitous in nature mostly due to ‘‘byproduct benefits’’ stemming from the intrinsic traits of one partner that generate an indirect and positive outcome for the other. Here we verify if myrmecotrophy (where plants obtain nutrients from the refuse of their associated ants) can explain the stability of the tripartite association between the myrmecophyte Hirtella physophora, the ant Allomerus decemarticulatus and an Ascomycota fungus. The plant shelters and provides the ants with extrafloral nectar. The ants protect the plant from herbivores and integrate the fungus into the construction of a trap that they use to capture prey ; they also provide the fungus and their host plant with nutrients. During a 9-month field study, we over-provisioned experimental ant colonies with insects, enhancing colony fitness (i.e., more winged females were produced). The rate of partial castration of the host plant, previously demonstrated, was not influenced by the experiment. Experimental plants showed higher d15N values (confirming myrmecotrophy), plus enhanced vegetative growth (e.g., more leaves produced increased the possibility of lodging ants in leaf pouches) and fitness (i.e., more fruits produced and more flowers that matured into fruit). This study highlights the importance of myrmecotrophy on host plant fitness and the stability of ant-myrmecophyte mutualisms.

P-76. Foucaud J, Rey O, Robert S, Crespin L, Orivel J, Facon B, Loiseau A, Jourdan H, Kenne M, Mbenoun Masse PS, Tindo M, Vonshak M & Estoup A. 2013. Thermotolerance adaptation to human-modified habitats occurs in the native range of the invasive ant Wasmannia auropunctata before long-distance dispersal. Evolutionary Applications, 6 : 721-734.

Abstract

Key evolutionary events associated with invasion success are traditionally thought to occur in the introduced, rather than the native range of species. In the invasive ant Wasmannia auropunctata, however, a shift in reproductive system has been demonstrated within the native range, from the sexual non-dominant populations of natural habitats to the clonal dominant populations of human-modified habitats. Because abiotic conditions of human-modified habitats are hotter and dryer, we performed lab experiments on workers from a set of native and introduced populations, to investigate whether these ecological and genetic transitions were accompanied by a change in thermotolerance and whether such changes occurred before establishment in the introduced range. Thermotolerance levels were higher in native populations from human-modified habitats than in native populations from natural habitats, but were similar in native and introduced populations from human-modified habitats. Differences in thermotolerance could not be accounted for by differences in body size. A scenario based on local adaptation in the native range before introduction in remote areas represents the most parsimonious hypothesis to account for the observed phenotypic pattern. These findings highlight the importance of human land use in explaining major contemporary evolutionary changes.

P-75. Lauth J, Malé PJG, Voglmayr H, Mayer VE, Dejean A & Orivel J. 2013. Isolation and characterization of polymorphic microsatellite loci in the ant-associated fungus Trimmatostroma sp. (Ascomycota : Chaetothyriales) using pyrosequencing technology. Molecular Ecology Resources, 13 : 546-549.

Abstract

Eleven microsatellite markers from the ant-associated fungus Trimmatostroma sp. (Chaetothyriales) were isolated and characterized using 454 FLX Titanium pyrosequencing technology. Two multiplex PCR sets were optimized for genotyping. The level of haploid genetic diversity varied from 0.421 to 0.878 for fungi associated with the ants Allomerus decemarticulatus and A. octoarticulatus in two populations from French Guiana. This set of microsatellite markers will be useful in addressing questions dealing with the specificity and the mode of transmission between the fungus and its associated ants.

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P-74. Ruiz-González MX, Lauth J, Leroy C, Jauneau A, Gryta H, Jargeat P, Dejean A & Orivel J. 2013. An efficient protocol for isolating melanised chaetothyrialean anamorphic fungi associated with plant-ants. Journal of Basic Microbiology, 53 : 98-100.

Abstract

Because of their ecological characteristics, slow growth rates and the presence of contaminants, Chaetothyriales fungi associated with structures built by tropical plant-ants can be difficult to isolate with standard procedures. Here, we describe an easy-to-use protocol for obtaining pure cultures by using cotton as a first substrate. We have further found by means of fluorescent stains that nuclei concentrate either in young hyphae or in the tips of the hyphae.

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P-73. Basset Y, Cizek L, Cuénoud P, Didham RK, Guilhaumon F, Missa O, Novotny V, Ødegaard F, Roslin T, Schmidl J, Tishechkin AK, Winchester NN, Roubik DW, Aberlenc HP, Bail J, Barrios H, Bridle JR, Castaño-Meneses G, Corbara B, Curletti G, Duarte da Rocha W, De Bakker D, Delabie JHC, Dejean A, Fagan LL, Floren A, Kitching RL, Medianero E, Miller SE, Gama de Oliveira E, Orivel J, Pollet M, Rapp M, Ribeiro SP, Roisin Y, Schmidt JB, Sørensen L & Leponce M. 2012. Arthropod diversity in a tropical forest. Science, 338 : 1481-1484.

Abstract

Most eukaryotic organisms are arthropods. Yet, their diversity in rich terrestrial ecosystems is still unknown. Here we produce tangible estimates of the total species richness of arthropods in a tropical rainforest. Using a comprehensive range of structured protocols, we sampled the phylogenetic breadth of arthropod taxa from the soil to the forest canopy in the San Lorenzo forest, Panama. We collected 6144 arthropod species from 0.48 hectare and extrapolated total species richness to larger areas on the basis of competing models. The whole 6000-hectare forest reserve most likely sustains 25,000 arthropod species. Notably, just 1 hectare of rainforest yields >60% of the arthropod biodiversity held in the wider landscape. Models based on plant diversity fitted the accumulated species richness of both herbivore and nonherbivore taxa exceptionally well. This lends credence to global estimates of arthropod biodiversity developed from plant models.

P-72. Rifflet A, Gavalda S, Tené N, Orivel J, Leprince J, Guilhaudis L, Génin E, Vétillard A & Treilhou M. 2012. Identification and characterization of a novel antimicrobial peptide from the venom of the ant Tetramorium bicarinatum. Peptides, 38:363-370.

Abstract

A novel antimicrobial peptide, named Bicarinalin, has been isolated from the venom of the ant Tetramorium bicarinatum. Its amino acid sequence has been determined by de novo sequencing using mass spectrometry and by Edman degradation. Bicarinalin contained 20 amino acid residues and was C-terminally amidated as the majority of antimicrobial peptides isolated to date from insect venoms. Interestingly, this peptide had a linear structure and exhibited no meaningful similarity with any known peptides. Antibacterial activities against Staphylococcus aureus and S. xylosus strains were evaluated using a synthetic replicate. Bicarinalin had a potent and broad antibacterial activity of the same magnitude as Melittin and other hymenopteran antimicrobial peptides such as Pilosulin or Defensin. Moreover, this antimicrobial peptide has a weak hemolytic activity compared to Melittin on erythrocytes, suggesting potential for development into an anti-infective agent for use against emerging antibiotic-resistant pathogens.
scenarios.

P-71. Rey O, Estoup A, Vonshak M, Loiseau A, Blanchet S, Calcaterra L, Chifflet L, Rossi JP, Kergoat G, Foucaud J, Orivel J, Leponce M, Schultz T & Facon B. 2012. Where do adaptive shifts occur during invasion ? A multidisciplinary approach to unravelling cold adaptation in a tropical ant species invading the Mediterranean zone. Ecology Letters, 15 : 1266-1275.

Abstract

Evolution may improve the invasiveness of populations, but it often remains unclear whether key adaptation events occur after introduction into the recipient habitat (i.e. post-introduction adaptation scenario), or before introduction within the native range (i.e. prior-adaptation scenario) or at a primary site of invasion (i.e. bridgehead scenario). We used a multidisciplinary approach to determine which of these three scenarios underlies the invasion of the tropical ant Wasmannia auropunctata in a Mediterranean region (i.e. Israel). Species distribution models (SDM), phylogeographical analyses at a broad geographical scale and laboratory experiments on appropriate native and invasive populations indicated that Israeli populations followed an invasion scenario in which adaptation to cold occurred at the southern limit of the native range before dispersal to Israel. We discuss the usefulness of combining SDM, genetic and experimental approaches for unambiguous determination of eco-evolutionary invasion scenarios.

P-70. Dejean A, Delabie JHC, Corbara B, Azémar F, Groc S, Orivel J, Leponce M. 2012. The ecology and feeding habits of the arboreal trap-jawed ant Daceton armigerum. PLoS ONE, 7 : e37683.

Abstract

Here we show that Daceton armigerum, an arboreal myrmicine ant whose workers are equipped with hypertrophied trap-jaw mandibles, is characterized by a set of unexpected biological traits including colony size, aggressiveness, trophobiosis and hunting behavior. The size of one colony has been evaluated at ca. 952,000 individuals. Intra- and interspecific aggressiveness were tested and an equiprobable null model used to show how D. armigerum colonies react vis-a-vis other arboreal ant species with large colonies ; it happens that D. armigerum can share trees with certain of these species. As they hunt by sight, workers occupy their hunting areas only during the daytime, but stay on chemical trails between nests at night so that the center of their home range is occupied 24 hours a day. Workers tend different Hemiptera taxa (i.e., Coccidae, Pseudococcidae, Membracidae and Aethalionidae). Through group-hunting, short-range recruitment and spread- eagling prey, workers can capture a wide range of prey (up to 94.12 times the mean weight of foraging workers).

P-69. Dejean A, Petitclerc F, Roux O, Orivel J & Leroy C. 2012. Does exogenic food benefit both partners in an ant-plant mutualism ? The case of Cecropia obtusa and its guest Azteca plant-ants. Comptes Rendus Biologie, 335 : 214-219.

Abstract

In the mutualisms involving the myrmecophyte Cecropia obtusa and Azteca ovaticeps or A. alfari, both predatory, the ants defend their host trees from enemies and provide them with nutrients (myrmecotrophy). A. ovaticeps provisioned with prey and then 15N-enriched food produced more individuals than did control colonies (not artificially provisioned). This was not true for A. alfari colonies, possibly due to differences in the degree of maturity of the colonies for the chosen range of host tree sizes (less than 3 m in height). Myrmecotrophy was demonstrated for both Azteca species as provisioning the ants with 15N-enriched food translated into higher d15N values in host plant tissues, indicating that nitrogen passed from the food to the plant. Thus, the predatory activity of their guest ants benefits the Cecropia trees not only because the ants protect them from defoliators since most prey are phytophagous insects but also because the plant absorbs nutrients.

P-68. Vantaux A, Roux O, Magro A & Orivel J. 2012. Evolutionary perspectives of myrmecophily in ladybirds. Psyche, Article ID 591570, doi:10.1155/2012/591570.

Abstract

Myrmecophiles are species that usually have developed specialized traits to cope with the aggressiveness of ants enabling them to live in their vicinity. Many coccinellid species are predators of Hemiptera ; the latter is also often protected by ants. Therefore these ladybirds frequently interact with ants, and some species have become myrmecophilous. In this paper, we aim to provide an overview of the evolution of myrmecophilous traits in ladybirds. We then discuss the costs and benefits of myrmecophily and the dietary shift to myrmecophagy observed in a few species.

P-67. Tindo M, Mbenoun Masse PS, Kenne M, Mony R, Orivel J, Doumtsop Fotio A, Fotso Kuaté A, Djiéto-Lordon C, Fomena A, Estoup A, Dejean A & Foucaud J. 2012. Current distribution and population dynamics of the little fire ant supercolony in Cameroon. Insectes Sociaux, 59 : 175-182

Abstract

The little fire ant, Wasmannia auropunctata, is native to Central America, but has been introduced into many parts of the world. We examined the current distribution of W. auropunctata in Cameroon, tested for aggression between workers from different parts of the country, and examined the genotypes of workers, queens, and males to evaluate the mating system. We found W. auropunctata at 36 sites in three provinces (Centre, East, and South). We found W. auropunctata only in human-disturbed habitats. Its spread appears to be primarily human mediated. Aggressive behaviour was almost non-existent between workers from different sites, indicating that there is only one supercolony in Cameroon. Our genetic analysis found that only one male/female pair of clones was introduced into Cameroon, probably from Gabon. No new male clonal lineage was identified, whereas new sexually derived female clonal lineages were noted. Apart from the genotype of the founding queen, which was well distributed but generally not dominant, a new clonal queen genotype emerged and was both omnipresent and dominant at most sites. These results may be useful in the development of management strategies.

P-66. Seipke R, Barke J, Ruiz-Gonzalez M, Orivel J, Yu DW, Hutchings MI. 2012. Fungus-growing Allomerus ants are associated with antibiotic-producing actinobacteria. Antonie van Leeuwenhoek, 101:443-447

Abstract

Fungus-growing attine ants use natural-product antibiotics produced by mutualist actinobacteria as \’weedkillers\’ in their fungal gardens. Here we report for the first time that fungus growing Allomerus ants, which lie outside the tribe Attini, are associated with antifungal-producing actinobacteria, which offer them protection against non-cultivar fungi isolated from their ant-plants.

P-65. Malé PJG, Leroy C, Dejean A, Quilichini A & Orivel J. 2012. An ant symbiont directly and indirectly limits its host plant’s reproductive success. Evolutionary Ecology, 26:55-63.

Abstract

In theory, mutualisms are intrinsically unstable, and the search for the maximum profit at the minimum cost should lead every mutualist to become a parasite. From an empirical point of view, mutualisms are ubiquitous and of major importance to ecosystems, suggesting the existence of mechanisms that enhance the maintenance of such relationships. We focused on the obligatory myrmecophytic association between the Neotropical plant Hirtella physophora (Chrysobalanaceae) and the ant Allomerus decemarticulatus (Myrmicinae). The plant shelters the ants in leaf pouches in exchange for protection from phytophagous insects. We experimentally demonstrated that the ants partially castrate their host plant by destroying almost two-thirds of its floral buds. The ants also impede pollination through their presence and interactions with pollinators. These results reveal that ant activity negatively affects the plant’s reproduction both directly and indirectly. This dual negative effect does not result in the complete castration of the plant. We also highlight major limitations to plant reproduction due to the spontaneous abscission of flowers and to the limited quantity and/or poor quality of the pollen. These limitations must not be overlooked since they can alter the outcome of the association of H. physophora with its ant partner. We therefore conclude that the evolutionary fate of the relationship depends on both ant castration intensity and obstacles to plant fertilization not related to the presence of ants.

P-64. Orivel J & Leroy C. 2011. The diversity and ecology of ant gardens (Hymenoptera : Formicidae ; Spermatophyta : Angiospermae). Myrmecological News, 14 : 73-85.

Abstract

Mutualistic interactions between ants and plants are important features of many ecosystems, and they can be divided into three main categories : dispersal and protective mutualisms and myrmecotrophy. In both the Neotropics and the Southeastern Asian Paleotropics, ant gardens (AGs), a particular type of ant-plant interaction, are frequent. To initiate AGs, ants integrate the seeds of certain epiphyte species into the carton of their nest. The development of the plants leads to the formation of a cluster of epiphytes rooted in the carton. They have been defined as one of the most complex associations between ants and plants known because of the plurispecific, but also specialized nature of the association involving several phylogenetically-distant ant and plant species. The aim of this review is to provide a synthesis of the diversity and ecology of AGs, including the outcomes experienced by the partners in the interaction and the direct and indirect impacts ant-garden ants have on the plant and arthropod communities.

P-63. Rifflet A, Tene A, Orivel J, Treilhou M, Dejean A & Vétillard A. 2011. Paralyzing action from a distance in an arboreal African ant species. PLoS ONE, 6 : e28571.

Abstract

Due to their prowess in interspecific competition and ability to catch a wide range of arthropod prey (mostly termites with which they are engaged in an evolutionary arms race), ants are recognized as a good model for studying the chemicals involved in defensive and predatory behaviors. Ants’ wide diversity of nesting habits and relationships with plants and prey types implies that these chemicals are also very diverse. Using the African myrmicine ant Crematogaster striatula as our focal species, we adopted a three-pronged research approach. We studied the aggressive and predatory behaviors of the ant workers, conducted bioassays on the effect of their Dufour gland contents on termites, and analyzed these contents. (1) The workers defend themselves or eliminate termites by orienting their abdominal tip toward the opponent, stinger protruded. The chemicals emitted, apparently volatile, trigger the recruitment of nestmates situated in the vicinity and act without the stinger having to come into direct contact with the opponent. Whereas alien ants competing with C. striatula for sugary food sources are repelled by this behavior and retreat further and further away, termites defend their nest whatever the danger. They face down C. striatula workers and end up by rolling onto their backs, their legs batting the air. (2) The bioassays showed that the toxicity of the Dufour gland contents acts in a time-dependent manner, leading to the irreversible paralysis, and, ultimately, death of the termites. (3) Gas chromatography-mass spectrometry analyses showed that the Dufour gland contains a mixture of mono- or polyunsaturated long-chain derivatives, bearing functional groups like oxo-alcohols or oxo-acetates. Electrospray ionization-mass spectrometry showed the presence of a molecule of 1584 Da that might be a large, acetylated alkaloid capable of splitting into smaller molecules that could be responsible for the final degree of venom toxicity.

P-62. Dejean A, Céréghino R, Carpenter JM, Corbara B, Hérault B, Rossi V, Leponce M, Orivel J, Bonal D. 2011. Climate change impact on Neotropical social wasps. PLoS ONE, 6:e27004.

Abstract

Establishing a direct link between climate change and fluctuations in animal populations through long-term monitoring is difficult given the paucity of baseline data. We hypothesized that social wasps are sensitive to climatic variations, and thus studied the impact of ENSO events on social wasp populations in French Guiana. We noted that during the 2000 La Niña year there was a 77.1% decrease in their nest abundance along ca. 5 km of forest edges, and that 70.5% of the species were no longer present. Two simultaneous 13-year surveys (1997–2009) confirmed the decrease in social wasps during La Niña years (2000 and 2006), while an increase occurred during the 2009 El Niño year. A 30-year weather survey showed that these phenomena corresponded to particularly high levels of rainfall, and that temperature, humidity and global solar radiation were correlated with rainfall. Using the Self-Organizing Map algorithm, we show that heavy rainfall during an entire rainy season has a negative impact on social wasps. Strong contrasts in rainfall between the dry season and the short rainy season exacerbate this effect. Social wasp populations never recovered to their pre-2000 levels. This is probably because these conditions occurred over four years ; heavy rainfall during the major rainy seasons during four other years also had a detrimental effect. On the contrary, low levels of rainfall during the major rainy season in 2009 spurred an increase in social wasp populations. We conclude that recent climatic changes have likely resulted in fewer social wasp colonies because they have lowered the wasps\’ resistance to parasitoids and pathogens. These results imply that Neotropical social wasps can be regarded as bio-indicators because they highlight the impact of climatic changes not yet perceptible in plants and other animals.

P-61. Rey O, Loiseau A, Facon B, Foucaud J, Orivel J, Cornuet JM, Robert S, Dobigny G, Delabie JHC, Mariano CSF & Estoup A. 2011. Meiotic recombination dramatically decreased in thelytokous queens of the little fire ant and their sexually produced workers. Molecular Biology and Evolution, 28 : 2591-2601.

Abstract

The little fire ant, Wasmannia auropunctata, displays a particular breeding system polymorphism. Classical haplo-diploid sexual reproduction between reproductive individuals occurs in some populations, whereas, in others, queens and males reproduce clonally. Workers are produced sexually and are sterile in both clonal and sexual populations. The evolutionary fate of the clonal lineages depends strongly on the underlying mechanisms allowing reproductive individuals to transmit their genomes to subsequent generations. We used several queen-offspring datasets to estimate the rate of transition from heterozygosity to homozygosity associated with recombination events at 33 microsatellite loci in thelytokous parthenogenetic queen lineages and compared these rates with theoretical expectations under various parthenogenesis mechanisms. We then used sexually produced worker families to define linkage groups for these 33 loci and to compare meiotic recombination rates in sexual and parthenogenetic queens. Our results demonstrate that queens from clonal populations reproduce by automictic parthenogenesis with central fusion. These same parthenogenetic queens produce normally segregating meiotic oocytes for workers, which display much lower rates of recombination (by a factor of 45) than workers produced by sexual queens. These low recombination rates also concern the parthenogenetic production of queen offspring, as indicated by the very low rates of transition from heterozygosity to homozygosity observed (from 0 to 2.8%). We suggest that the combination of automixis with central fusion and a major decrease in recombination rates allows clonal queens to benefit from thelytoky while avoiding the potential inbreeding depression resulting from the loss of heterozygosity during automixis. In sterile workers, the strong decrease of recombination rates may also facilitate the conservation over time of some coadapted allelic interactions within chromosomes, that might confer an adaptive advantage in habitats disturbed by human activity, where clonal populations of W. auropunctata are mostly found.

P-60. Leroy C, Séjalon-Delmas N, Jauneau A, Ruiz-González MX, Gryta H, Jargeat P, Corbara B, Dejean A & Orivel J. 2011. Trophic mediation by a fungus in an ant–plant mutualism. Journal of Ecology, 99 : 583-590.

Abstract

1. Plants often rely on external, mutualistic partners to survive and reproduce in resource-limited environments or for protection from enemies. Such interactions, including mycorrhizal symbioses and ant–plant associations, are widespread and play an important role at the ecosystem and community levels. In ant–plant mutualisms, the plants may benefit from both the protection provided by the presence of ants and from the nutrients absorbed from insect debris. However, the role of third partners in plant nutrition, particularly ant-associated fungi, has never before been demonstrated.

2. We investigate this issue in the ant–plant Hirtella physophora. In this model system, Allomerus decemarticulatus ants are involved in two, highly specific interactions : first, with their host plant, and, secondly, with a fungus that they actively manipulate. Moreover, the ants combine both plant trichomes and fungal hyphae to make a trap to capture prey.

3. We empirically demonstrate the existence of a third type of interaction between the fungus and the plant through the use of both experimental enrichments with stable isotopes (15N) and histological approaches. The fungus growing in the galleries plays a role in providing nutrients to the host plant, in addition to the structural role it plays for the ants. Fungus-facilitated nitrogen uptake occurs mainly in old domatia, where abundant hyphae are in close contact with the plant cells. Whether the fungi inside the domatia and those in the galleries are the same is still uncertain.

4. Synthesis.Together,our results show that a fungal partner in an ant–plant mutualism can benefit the plant by improving its nutrient uptake, and they demonstrate the existence of a true tripartite mutualism in this system. Our results add further evidence to the notion that interpretations of some ant–plant symbioses as purely protective mutualisms have overlooked these nutritional aspects.

P-59. Ruiz-González MX, Malé PJG, Leroy C, Dejean A, Gryta H, Jargeat P, Quilichini A & Orivel J. 2011. Specific, non-nutritional association between an Ascomycete fungus and Allomerus plant-ants. Biology Letters, 7 : 475-479.

Abstract

Ant–fungus associations are well known from attine ants, whose nutrition is based on a symbiosis with basidiomycete fungi. Otherwise, only a few non-nutritional ant–fungus associations have been recorded to date. Here we focus on one of these associations involving Allomerus plant-ants that build galleried structures on their myrmecophytic hosts in order to ambush prey. We show that this association is not opportunistic because the ants select from a monophyletic group of closely related fungal haplotypes of an ascomycete species from the order Chaetothyriales that consistently grows on and has been isolated from the galleries. Both the ants’ behaviour and an analysis of the genetic population structure of the ants and the fungus argue for host specificity in this interaction. The ants’ behaviour reveals a major investment in manipulating, growing and cleaning the fungus. A molecular analysis of the fungus demonstrates the widespread occurrence of one haplotype and many other haplotypes with a lower occurrence, as well as significant variation in the presence of these fungal haplotypes between areas and ant species. Altogether, these results suggest that such an interaction might represent an as-yet undescribed type of specific association between ants and fungus in which the ants cultivate fungal mycelia to strengthen their hunting galleries

P-58. Orivel J, Lambs L, Malé PJG, Leroy C, Grangier J, Otto T, Quilichini A & Dejean A. 2011. Dynamics of the association between a long-lived understory myrmecophyte and its specific associated ants. Oecologia, 165 : 369-376.

Abstract

Myrmecophytic symbioses are widespread in tropical ecosystems and their diversity makes them useful tools for understanding the origin and evolution of mutualisms. Obligate ant–plants, or myrmecophytes, provide a nesting place, and, often, food to a limited number of plant–ant species. In exchange, plant–ants protect their host plants from herbivores, competitors and pathogens, and can provide them with nutrients. Although most studies to date have highlighted a similar global pattern of interactions in these systems, little is known about the temporal structuring and dynamics of most of these associations. In this study we focused on the association between the understory myrmecophyte Hirtella physophora (Chrysobalanaceae) and its obligate ant partner Allomerus decemarticulatus (Myrmicinae). An examination of the life histories and growth rates of both partners demonstrated that this plant species has a much longer lifespan (up to about 350 years) than its associated ant colonies (up to about 21 years). The size of the ant colonies and their reproductive success were strongly limited by the available nesting space provided by the host plants. Moreover, the resident ants positively aVected the vegetative growth of their host plant, but had a negative effect on its reproduction by reducing the number of flowers and fruits by more than 50%. Altogether our results are important to understanding the evolutionary dynamics of ant–plant symbioses. The highly specialized interaction between long-lived plants and ants with a shorter lifespan produces an asymmetry in the evolutionary rates of the interaction which, in return, can affect the degree to which the interests of the two partners converge.

P-57. Groc S, Delabie JHC, Longino JT, Orivel J, Majer JE, Vasconcelos HL & Dejean A. 2010. A new method based on taxonomic sufficiency to simplify studies on Neotropical ant assemblages. Biological Conservation, 143 : 2832-2839.

Abstract

Insects, particularly ants, are good bioindicators of the state of ecosystems. Nevertheless, incorporating them into conservation surveys is expensive due to problems associated with their identification, which is exacerbated by the fact that there are fewer and fewer taxonomists working today. ‘‘Taxonomic sufficiency” (TS), which identifies organisms to a level of taxonomic resolution sufficient enough to satisfy the objectives of a study, has never been applied to Neotropical ant communities. We analysed five Neotropical datasets representing ant assemblages collected with different sampling methods in various habitats. We first treated them using two complementary and cumulative TS methods, higher-taxon and ‘‘indicator taxa” surrogacies, before testing a new approach called ‘‘mixed-level method” that combines the two previous approaches. For the higher-taxon surrogacy, we showed that, above species, genus is the most informative taxonomic level. Then, mixed-level method provided more information on ant assemblages than did the two others, even though the ‘‘indicator taxa” surrogacy was based on relevant indicator gen- era. Although habitat type has no effect on its efficiency, this new method is influenced by the dataset structure and the type of sampling method used to collect data. We have thus developed a new method for analyzing Neotropical ant faunas that enables the taxonomic work linked to the identification of prob- lematic species to be significantly reduced, while conserving most of the information on the ant assem- blage. This method should enhance the work of Neotropical entomologists not specialised in taxonomy, particularly those concerned with biological conservation and indication.

P-56. Dejean A, Leroy C, Corbara B, Céréghino R, Roux O, Hérault B, Rossi V, Guerrero RJ, Delabie JHC, Orivel J & Boulay R. 2010. A temporary social parasite of tropical plant-ants improves the fitness of a myrmecophyte. Naturwissenschaften, 97 : 925-934.

Abstract

Myrmecophytes offer plant-ants a nesting place in exchange for protection from their enemies, particularly defoliators. These obligate ant–plant mutualisms are common model systems for studying factors that allow horizontally transmitted mutualisms to persist since parasites of ant–myrmecophyte mutualisms exploit the rewards provided by host plants whilst providing no protection in return. In pioneer formations in French Guiana, Azteca alfari and Azteca ovaticeps are known to be mutualists of myrmecophytic Cecropia (Cecropia ants). Here, we show that Azteca andreae, whose colonies build carton nests on myrmecophytic Cecropia, is not a parasite of Azteca–Cecropia mutualisms nor is it a temporary social parasite of A. alfari ; it is, however, a temporary social parasite of A. ovaticeps. Contrarily to the two mutualistic Azteca species that are only occasional predators feeding mostly on hemipteran honeydew and food bodies provided by the host trees, A. andreae workers, which also attend hemi- pterans, do not exploit the food bodies. Rather, they employ an effective hunting technique where the leaf margins are fringed with ambushing workers, waiting for insects to alight. As a result, the host trees’ fitness is not affected as A. andreae colonies protect their foliage better than do mutualistic Azteca species resulting in greater fruit production. Yet, contrarily to mutualistic Azteca, when host tree development does not keep pace with colony growth, A. andreae workers forage on surrounding plants ; the colonies can even move to a non-Cecropia tree.

P-55. Malé PJG, Malausa T, Martin JF, Orivel J & Quilichini A. 2010. Isolation and characterization of polymorphic microsatellite loci in the ant-plant Hirtella physophora (Chrysobalanaceae) using pyrosequencing technology. Molecular Ecology Resources, 10 : 1106-1108.

Abstract

The new generation 454 FLX Titanium pyrosequencing technology was used to isolate 503 novel microsatellite loci in the myrmecophytic plant Hirtella physophora. Four multiplex PCR sets were optimized in order to genotype 16 polymorphic microsatellite loci. The level of genetic diversity was assessed in two populations from French Guiana. The number of alleles per locus ranged from two to 13 and observed heterozygosity varied from 0.11 to 0.92. Cross-species amplification of these loci was successfully demonstrated in additional species of the same plant family Chrysobalanaceae. This set of microsatellite markers will be useful in addressing questions dealing with the mating system and population genetic structure of Chrysobalanaceae in general and H. physophora in particular.

P-54. Malé PJG, Loiseau A, Estoup A, Quilichini A & Orivel J. 2010. Characterization of polymorphic microsatellite loci in the neotropical plant-ant Allomerus decemarticulatus (Formicidae : Myrmicinae) and multiplexing with other microsatellites from the ant subfamily Myrmicinae. European Journal of Entomology, 107 : 673-675.

Abstract

Five polymorphic microsatellite loci of the arboreal ant Allomerus decemarticulatus (Myrmicinae) were isolated and characterized. The amplification and polymorphism of seven additional microsatellite loci, previously developed for the ant species A. octoarticulatus and Wasmannia auropunctata, were also tested and the amplification conditions necessary for genotyping the complete set of 12 multiplexed markers in A. decemarticulatus determined. The number of alleles per locus ranged from three to 15 and observed heterozygosity varied from 0.09 to 0.95. Cross-species amplification of these loci was also successfully achieved in additional species of the same ant subfamily, Myrmicinae. This set of microsatellite markers will be used in studies on the mating system and population genetic structure of Myrmicinae in general and A. decemarticulatus in particular.

P-53. Dejean A, Leroy C, Corbara B, Roux O, Céréghino R, Orivel J & Boulay R. 2010. Arboreal ants use the “Velcro® principle” to capture very large prey. PloS ONE, 5 : e11331.

Abstract

Plant-ants live in a mutualistic association with host plants known as ‘‘myrmecophytes’’ that provide them with a nesting place and sometimes with extra-floral nectar (EFN) and/or food bodies (FBs) ; the ants can also attend sap-sucking Hemiptera for their honeydew. In return, plant-ants, like most other arboreal ants, protect their host plants from defoliators. To satisfy their nitrogen requirements, however, some have optimized their ability to capture prey in the restricted environment represented by the crowns of trees by using elaborate hunting techniques. In this study, we investigated the predatory behavior of the ant Azteca andreae which is associated with the myrmecophyte Cecropia obtusa. We noted that up to 8350 ant workers per tree hide side-by-side beneath the leaf margins of their host plant with their mandibles open, waiting for insects to alight. The latter are immediately seized by their extremities, and then spread-eagled ; nestmates are recruited to help stretch, carve up and transport prey. This group ambush hunting technique is particularly effective when the underside of the leaves is downy, as is the case for C. obtusa. In this case, the hook-shaped claws of the A. andreae workers and the velvet-like structure of the underside of the leaves combine to act like natural Velcro that is reinforced by the group ambush strategy of the workers, allowing them to capture prey of up to 13,350 times the mean weight of a single worker.

P-52. Ruiz-González MX, Corbara B, Leroy C, Dejean A & Orivel J. 2010. The weaver wasp : spinning fungus into a nest. Biotropica, 42 : 402-404.

Abstract

Wasp nests range from simple to complex structures made of paper or mud. Here, we show that a Neotropical wasp of the genus Nitela builds its nest entirely by weaving endophytic fungal hyphae and spider silk harvested from the leaves growing in the understory of the rain forest in French Guiana.

P-51. Leroy C, Jauneau A, Quilichini A, Dejean A & Orivel J. 2010. Comparative structure and ontogeny of the foliar domatia in three Neotropical myrmecophytes. American Journal of Botany, 94 : 557-565.

Abstract

The origin and timing of the appearance of leaf domatia during the ontogeny of plants are important evolutionary traits driving the maintenance of ant–plant associations. In this study conducted in French Guiana on Hirtella physophora, Maieta guianensis, and Tococa guianensis, we focused on the formation and development of leaf domatia having different morphological origins. We modeled the timing of the onset of these domatia, then compared their morpho-anatomical structure. Although the ontogenetic development of the domatia differed between species, they developed very early in the plant’s ontogeny so that we did not note differences in the timing of the onset of these domatia. For H. physophora seedlings, a transitional leaf forms before the appearance of fully developed domatia, whereas in M. guianensis and T. guianensis the domatia forms abruptly without transitional leaves. Moreover, in all cases, the morpho-anatomical structure of the domatia differed considerably from the lamina. All three species had similar morpho-anatomical characteristics for the domatia, indicating a convergence in their structural and functional characteristics. This convergence between taxonomically distant plant species bearing domatia having different morphological origins could be interpreted as a product of the plant’s evolution toward the morphology and anatomy most likely to maximize ant recruitment and long-term residence.

P-50. Vantaux A, Roux O, Magro A, Tene Ghomsi N, Gordon RD, Dejean A & Orivel J. 2010. Host-specific myrmecophily and myrmecophagy in the tropical coccinellid Diomus thoracicus. Biotropica, 42 : 622-629.

Abstract

A variety of arthropods, particularly insects, have developed myrmecophilous interactions with ants to gain access to resources and/or for protection. Among these myrmecophiles, only a few examples have been documented in the Coccinellidae, most of them involving species able to feed on ant-tended Hemiptera. We report here a new case of obligate myrmecophily in the coccinellid Diomus thoracicus. Larvae are invariably and exclusively found in the nests of the ant Wasmannia auropunctata and seem to rely on ant brood as their only food source. Not only do ant workers show no aggressiveness toward the D. thoracicus larvae in their behavioral interactions at the colonial level, but also at the species level ; while coccinellid adults are always attacked. The integration of the larvae inside of the ant nests is based on their chemical mimicry of the host’s cuticular cues. Therefore, given the presence of the D. thoracicus larvae inside of the ant’s nest, their predation on Wasmannia brood and their chemical mimicry, this species can be considered a specific parasite of W. auropunctata. Overall, this new case of myrmecophily not only specifically involves a highly invasive ant species, but also provides insights into the evolution of myrmecophily and myrmecophagy in coccinellids

P-49. Roux O, Billen J, Orivel J & Dejean A. 2010. An overlooked mandibular-rubbing behavior used during recruitment by the african weaver ant, Oecophylla longinoda. PLoS ONE 5 : e8957.

Abstract

In Oecophylla, an ant genus comprising two territorially dominant arboreal species, workers are known to (1) use anal spots to mark their territories, (2) drag their gaster along the substrate to deposit short-range recruitment trails, and (3) drag the extruded rectal gland along the substrate to deposit the trails used in long-range recruitment. Here we study an overlooked but important marking behavior in which O. longinoda workers first rub the underside of their mandibles onto the substrate, and then—in a surprising posture—tilt their head and also rub the upper side of their mandibles. We demonstrate that this behavior is used to recruit nestmates. Its frequency varies with the rate at which a new territory, a sugary food source, a prey item, or an alien ant are discovered. Microscopy analyses showed that both the upper side and the underside of the mandibles possess pores linked to secretory glands. So, by rubbing their mandibles onto the substrate, the workers probably spread a secretion from these glands that is involved in nestmate recruitment.

P-48. Foucaud J, Orivel J, Loiseau A, Delabie JHC, Jourdan H, Konghouleux D, Vonshak M, Tindo M, Mercier JL, Fresneau D, Mikissa JB, McGlynn T, Mikheyev AS, Oettler J & Estoup A. 2010. Worldwide invasion by the little fire ant : routes of introduction and eco-evolutionary pathways. Evolutionary Applications, 3 : 363-374.

Abstract

Biological invasions are generally thought to occur after human aided migration to a new range. However, human activities prior to migration may also play a role. We studied here the evolutionary genetics of introduced populations of the invasive ant Wasmannia auropunctata at a worldwide scale. Using microsatellite markers, we reconstructed the main routes of introduction of the species. We found three main routes of introduction, each of them strongly associated to human history and trading routes. We also demonstrate the overwhelming occurrence of male and female clonality in introduced populations of W. auropunctata, and suggest that this particular reproduction system is under selection in human-modified habitats. Together with previous researches focused on native populations, our results suggest that invasive clonal populations may have evolved within human modified habitats in the native range, and spread further from there. The evolutionarily most parsimonious scenario for the emergence of invasive populations of the little fire ant might thus be a two-step process. The W. auropunctata case illustrates the central role of humans in biological change, not only due to changes in migration patterns, but also in selective pressures over species.

P-47. Foucaud J, Estoup A, Loiseau A, Rey O & Orivel J. 2010. Thelytokous parthenogenesis, male clonality and genetic caste determination in the little fire ant : new evidence and insights from the lab. Heredity, 105 : 205-212.

Abstract

Previous studies indicate that some populations of the little fire ant, Wasmannia auropunctata, display an unusual reproduction system polymorphism. Although some populations have a classical haplodiploid reproduction system, in other populations queens are produced by thelytokous parthenogenesis, males are produced by a male clonality system and workers are produced sexually. An atypical genetic caste determination system was also suggested. However, these conclusions were indirectly inferred from genetic studies on field population samples. Here we set up experimental laboratory nests that allow the control of the parental relationships between individuals. The queens heading those nests originated from either putatively clonal or sexual populations. We characterized the male, queen and worker offspring they produced at 12 microsatellite loci. Our results unambiguously confirm the unique reproduction system polymorphism mentioned above and that male clonality is strictly associated with thelytokous parthenogenesis. We also observed direct evidence of the rare production of sexual gynes and arrhenotokous males in clonal populations. Finally, we obtained evidence of a genetic basis for caste determination. The evolutionary significance of the reproduction system polymorphism and genetic caste determination as well as future research opportunities are discussed.

P-46. Foucaud J, Orivel J, Fournier D, Delabie JHC, Loiseau A, Le Breton J, Cerdan P & Estoup A. 2009. Reproduction system, social organization, human disturbance and ecological dominance in native populations of the little fire ant, Wasmannia auropunctata. Molecular Ecology, 18 : 5059-5073.

Abstract

The invasive ant species Wasmannia auropunctata displays both ecologically dominant and non-dominant populations within its native range. Three factors could theoretically explain the ecological dominance of some native populations of W. auropunctata : (i) its clonal reproductive system, through demographic and/or adaptive advantages ; (ii) its unicolonial social organization, through lower intraspecific and efficient interspecific competition ; (iii) the human disturbance of its native range, through the modification of biotic and abiotic environmental conditions. We used microsatellite markers and behavioural tests to uncover the reproductive modes and social organization of dominant and non-dominant native populations in natural and human-modified habitats. Microsatellite and mtDNA data indicated that dominant and non-dominant native populations (supercolonies as determined by aggression tests) of W. auropunctata did not belong to different evolutionary units. We found that the reproductive system and the social organization are neither necessary nor sufficient to explain W. auropunctata ecological dominance. Dominance rather seems to be set off by unknown ecological factors altered by human activities, as all dominant populations were recorded in human-modified habitats. The clonal reproductive system found in some populations of W. auropunctata may however indirectly contribute to its ecological dominance by allowing the species to expand its environmental niche, through the fixation over time of specific combinations of divergent male and female genotypes. Unicoloniality may rather promote the range expansion of already dominant popula- tions than actually trigger ecological dominance. The W. auropunctata model illustrates the strong impact of human disturbance on species’ ecological features and the adaptive potential of clonal reproductive systems.

GIF

P-45. Szilagyi A, Scheuring I, Edwards DP, Orivel J & Yu DW. 2009. The evolution of intermediate castration virulence and ant coexistence in a spatially structured environment. Ecology Letters, 12 : 1306-1316.

Abstract

Theory suggests that spatial structuring should select for intermediate levels of virulence in parasites, but empirical tests are rare and have never been conducted with castration (sterilizing) parasites. To test this theory in a natural landscape, we construct a spatially explicit model of the symbiosis between the ant-plant Cordia nodosa and its two, protecting ant symbionts, Allomerus and Azteca. Allomerus is also a castration parasite, preventing fruiting to increase colony fecundity. Limiting the dispersal of Allomerus and host plant selects for intermediate castration virulence. Increasing the frequency of the mutualist, Azteca, selects for higher castration virulence in Allomerus, because seeds from Azteca-inhabited plants are a public good that Allomerus exploits. These results are consistent with field observations and, to our knowledge, provide the first empirical evidence supporting the hypothesis that spatial structure can reduce castration virulence and the first such evidence in a natural landscape for either mortality or castration virulence.

P-44. Orivel J, Grangier J, Foucaud J, Le Breton J, Andrès FX, Jourdan H, Delabie JHC, Fournier D, Cerdan P, Estoup A, Facon B & Dejean A. 2009. Ecologically heterogeneous populations of the invasive ant Wasmannia auropunctata within its native and introduced ranges. Ecological Entomology, 34 : 504-512.

Abstract

1. The biology of most invasive species in their native geographical areas remains largely unknown. Such studies are, however, crucial in shedding light on the ecological and evolutionary processes underlying biological invasions.
2. The present study focuses on the little fire ant Wasmannia auropunctata, a species native to Central and South America that has been widely introduced and which has become invasive throughout the tropics. We characterise and compare several ecological traits of native populations in French Guiana with those in one of its introduced ranges, New Caledonia.
3. We found ecologically heterogeneous populations of W. auropunctata coexisting in the species’ native geographical area. First, we found populations restricted to naturally perturbed areas (particularly floodplains) within the primary forest, and absent from the surrounding forest areas. These populations were characterised by low nest and worker densities. Second, we found dominant populations in recent anthropogenic areas (e.g. secondary forest or forest edge along road) characterised by high nest and worker densities, and associated with low ant species richness. The local dominance of W. auropunctata in such areas can be due to the displacement of other species (cause) or the filling-up of empty habitats unsuitable to other ants (effect). With respect to their demographic features and ant species richness, the populations of native anthropogenic habitats were to a large extent similar to the invasive populations introduced into remote areas.
4. The results point to the need for greater research efforts to better understand the ecological and demographic features of invasive species within their native ranges.

P-43. Groc S, Orivel J, Dejean A, Martin JM, Etienne MP, Corbara B & Delabie JHC. 2009. Baseline study of the leaf-litter ant fauna in a French Guianese forest. Insect Conservation and Diversity, 2 : 183-193.

Abstract

1. Leaf-litter ants represent a major component of biodiversity and are excellent bioindicators reflecting the health of terrestrial ecosystems. This study, conducted in an unspoiled forest near the Nouragues Research Station, represents the first inventory of leaf-litter ant diversity conducted in French Guiana, and so can be considered as the baseline dataset for ants in this country.
2. Ants were extracted from the leaf-litter using the Ants of the Leaf Litter Protocol, along an altitudinal gradient at four forest sites, including an inselberg.
3. A total of 196 ant species representing 46 genera distributed over eight subfamilies were collected. Four distinct communities spread over a gradient of diversity were thus identified : the liana forest was the most species-rich (140 species) followed by the forested plateau (102 species), the transition forest (87 species) and the forest at the top of the inselberg (71 species).
4. The discovery of species new to science plus several species recorded for the first time in French Guiana, coupled with the particular context of this area, suggests that the Nouragues Research Station might represent a centre of endemism. Once completed, this leaf-litter ant dataset will contribute greatly to the knowledge of ant biodiversity in French Guiana, and has the potential to progressively become an indispensable tool for country-wide conservation planning programmes.

P-42. Grangier J, Dejean A, Malé PJG, Solano PJ & Orivel J. 2009. Mechanisms driving the specificity of a myrmecophyte-ant association. Biological Journal of the Linnean Society, 97 : 90-97.

Abstract

In the understory of pristine Guianese forests, the myrmecophyte Hirtella physophora almost exclusively shelters colonies of the plant-ant Allomerus decemarticulatus in its leaf pouches. We experimentally tested three non-mutually exclusive hypotheses concerning phenomena that can determine the species specificity of this association throughout the foundation stage of the colonies : (1) interspecific competition results in the overwhelming presence of A. decemarticulatus queens or incipient colonies ; (2) exclusion filters prevent other ant species from entering the leaf pouches ; and (3) host-recognition influences the choice of founding queens, especially A. decemarticulatus. Neither interspecific competition, nor the purported exclusion filters that we examined play a major role in maintaining the specificity of this association. Unexpectedly, the plant trichomes lining the domatia appear to serve as construction material during claustral foundation rather than as a filter. Finally, A. decemarticulatus queens are able to identify their host plant from a distance through chemical and/or visual cues, which is rarely demonstrated in studies on obligatory ant–plant associations. We discuss the possibility that this specific host-recognition ability could participate in shaping a compartmentalized plant-ant community where direct competition between ant symbionts is limited.

P-41. Dejean A, Grangier J, Leroy C & Orivel J. 2009. Predation and aggressiveness in host plant protection : a generalization using ants from the genus, Azteca. Naturwissenschaften, 96 : 57-63.

Abstract

In studying the ant genus Azteca, a Neotropical group of arboreal species, we aimed to determine the extent to which the ants use predation and/or aggressiveness to protect their host plants from defoliating insects. We compared a territorially dominant, carton-nester, Azteca chartifex, and three plant-ant species. Azteca alfari and Azteca ovaticeps are associated with the myrmecophyte Cecropia (Cecropiaceae) and their colonies shelter in its hollow branches ; whereas Azteca bequaerti is associated with Tococa guianensis (Melastomataceae) and its colonies shelter in leaf pouches situated at the base of the laminas. Whereas A. bequaerti workers react to the vibrations transmitted by the lamina when an alien insect lands on a leaf making it unnecessary for them to patrol their plant, the workers of the three other species rather discover prey by contact. The workers of all four species use a predatory behaviour involving spread-eagling alien insects after recruiting nestmates at short range, and, in some cases, at long range. Because A. alfari and A. ovaticeps discard part of the insects they kill, we deduced that the workers’ predatory behaviour and territorial aggressiveness combine in the biotic defence of their host tree.

P-40. Dejean A., Grangier J., Leroy C & Orivel J 2008 Host plant protection by arboreal ants : looking for a pattern in locally induced responses. Evolutionary Ecology Research, 10 : 1217-1223.

Abstract

Background : Among arboreal ants, both territorially dominant species and plant-ants (e.g. species associated with myrmecophytes or plants housing them in hollow structures) protect their host trees against defoliators. Yet, locally induced responses, or the recruitment of nest-mates when a worker discovers a wound on its host-tree, were only noted in plant-ants. We wondered whether this might be due to the examination of the phenomenon being restricted to only six plant-ant species belonging to four genera. Based on the ant genus Azteca, a Neotropical group of arboreal species, we compared five species. The territorially dominant, carton-nester A. chartifex, three plant-ant species [A. alfari and A. ovaticeps associated with myrmecophitic Cecropia (Cecropiaceae), and A. bequaerti associated with Tococa guianensis (Melastomataceae)], and A. schimperi thought to be a temporary social parasite of true Cecropia ants.
Methods : We artificially inflicted wounds to the foliage of the host tree of the different ant species. We then compared the number of workers on wounded versus control leaves.
Results : We noted a locally induced response in the three plant-ant species as well as in the territorially dominant species, but very slightly so in A. schimperi.

P-39. Gibernau M, Orivel J, Dejean A, Delabie J & Barabé D. 2008. Flowering as a key factor in ant-Philodendron interactions. Journal Tropical Ecology, 24 : 689-692.

Abstract

The Araceae, a monocotyledon family of 3000 mainly tropical species, has only a few known cases of associations with ants. Hence, no aroid is known to have strict relationships with ants or to be a myrmecophyte.
Philodendron solimoesense is a hemi-epiphytic aroid species found in upland or riverine forests where it develops on sandy and flooded soils, as was the case in our study site. Like other species of the genus, P. solimoesense produces EFN on bud bracts, the petiole, the base of the leaf lamina and the spathe of the inflorescence, suggesting a diffuse relationship with ants. Solitary inflorescences, arising vertically from the petiolar sheath at the base of the leaves, are thermogenic and pollinated by dynastine beetles. At maturity the closed spathe abscises from the base, exposing ripe fruits to frugivorous animals. After fruit dispersal, the spadix falls, breaking above the peduncle, which is hollow and remains inserted in the petiolar sheath. In this study we hypothesized that the P. solimoesense petiolar sheaths can serve as durable shelters for ant colonies, making this plant species a possible myrmecophyte.

P-38. Grangier J, Dejean A, Malé PJ & Orivel J. 2008. Indirect defense in a highly specific ant-plant mutualism. Naturwissenschaften, 95 : 909-916.

Abstract

Although associations between myrmecophytes and their plant ants are recognized as a particularly effective form of protective mutualism, their functioning remains incompletely understood. This field study examined the ant-plant Hirtella physophora and its obligate ant associate Allomerus decemarticulatus. We formulated two hypotheses on the highly specific nature of this association : (1) Ant presence should be correlated with a marked reduction in the amount of herbivory on the plant foliage ; (2) ant activity should be consistent with the \"optimal defense\" theory predicting that the most vulnerable and valuable parts of the plant are the best defended. We validated the first hypothesis by demonstrating that for ant-excluded plants, expanding leaves, but also newly matured ones in the long term, suffered significantly more herbivore damage than ant-inhabited plants. We showed that A. decemarticulatus workers represent both constitutive and inducible defenses for their host, by patrolling its foliage and rapidly recruiting nestmates to foliar wounds. On examining how these activities change according to the leaves’ developmental stage, we found that the number of patrolling ants dramatically decreased as the leaves matured, while leaf wounds induced ant recruitment regardless of the leaf’s age. The resulting level of these indirect defenses was roughly proportional to leaf vulnerability and value during its development, thus validating our second hypothesis predicting optimal protection. This led us to discuss the factors influencing ant activity on the plant’s surface. Our study emphasizes the importance of studying both the constitutive and inducible components of indirect defense when evaluating its efficacy and optimality.

P-37. Dejean A, Grangier J, Leroy C, Orivel J & Gibernau M. 2008. Nest site selection and induced response in a dominant arboreal ant species. Naturwissenschaften, 95 : 885-889.

Abstract

It is well known that arboreal ants, both territorially dominant species and plant ants (e.g., species associated with myrmecophytes or plants housing them in hollow structures), protect their host trees from defoliators. Nevertheless, the presence of an induced defense, suggested by the fact that the workers discovering a leaf wound recruit nestmates, is only known for plant ants. Based on the results from a field study, we show here (1) that colonies of Azteca chartifex, a territorially dominant, neotropical arboreal ant species, mostly selected Goupia glabra (Goupiaceae) trees in which to build their principal carton nests and (2) that plant signals induced workers to recruit nestmates, which patrol the leaves, likely providing the plant with a biotic defense. Furthermore, the number of recruited workers was clearly higher on G. glabra, their most frequently selected host tree species, than on other tree species. These results show that contrary to what was previously believed, induced responses are also found in territorially dominant arboreal ants and so are not limited to the specific associations between myrmecophytes and plant ants

P-36. Grangier J, Orivel J, Negrini M & Dejean A. 2008. Low intraspecific aggressiveness in two obligate plant-ant species. Insectes Sociaux, 55 : 238-240.

Abstract

Little is known about the aggressiveness of plant-ants typically living in isolated trees nor about how that aggressiveness varies based on this isolation. Here, we examine intra- and interspecific aggressiveness between workers of two Allomerus species associated with two different myrmecophytes. In both cases, the level of intraspecific aggressiveness is very low whatever the distance separating the tested nests, while interspecific conflicts are always violent. Similar patterns of aggressiveness have been reported in various ant species, but the strictly arboreal life of Allomerus ants associated with the isolation of their adult colonies highlight different ecological conditions that might explain the lack of aggressiveness between conspecifics.

P-35. Leroy C, Jauneau A, Quilichini A, Dejean A & Orivel J. 2008. Comparison between the anatomical and morphological structure of leaf blades and foliar domatia in the ant-plant Hirtella physophora (Chrysobalanaceae). Annals of Botany, 101 : 501-507.

Abstract

Background and Aims Myrmecophytes, or ant-plants, are characterized by their ability to shelter colonies of some ant species in hollow structures, or ant-domatia, that are often formed by hypertrophy of the internal tissue at specific locations (i.e. trunk, branches, thorns and leaf pouches). In Hirtella physophora (Chrysobalanaceae), the focal species of this study, the ant-domatia consist of leaf pouches formed when the leaf rolls over onto itself to create two spheres at the base of the blade.
Methods The morphological and anatomical changes through which foliar ant-domatia developed from the laminas are studied for the first time by using fresh and fixed mature leaves from the same H. physophora individuals.
Key results Ant-domatia were characterized by larger extra-floral nectaries, longer stomatal apertures and lower stomatal density. The anatomical structure of the domatia differed in the parenchymatous tissue where palisade and spongy parenchyma were indistinct ; chloroplast density was lower and lignified sclerenchymal fibres were more numerous compared with the lamina. In addition, the domatia were thicker than the lamina, largely because the parenchymatous and epidermal cells were enlarged.
Conclusions Herein, the morphological and anatomical changes that permit foliar ant-domatia to be defined as a specialized leaf structure are highlighted. Similarities as well as structural modifications in the foliar ant-domatia compared with the lamina are discussed from botanical, functional and mutualistic points of view. These results are also important to understanding the reciprocal evolutionary changes in traits and, thus, the coevolutionary processes occurring in insect–plant mutualisms.

P-34. Dejean A, Djiéto-Lordon C & Orivel J. 2008. The plant-ant Tetraponera aethiops (Pseudomyrmecinae) protects its host myrmecophyte Barteria fistulosa (Passifloraceae) through aggressiveness and predation. Biological Journal of the Linnean Society, 93 : 63-69.

Abstract

Plant ants generally provide their host myrmecophytes (i.e. plants that shelter a limited number of ant species in hollow structures) protection from defoliating insects, but the exact nature of this protection is poorly known. It was with this in mind that we studied the association between Tetraponera aethiops F. Smith (Pseudomyrmecinae) and its specific host myrmecophyte Barteria fistulosa Mast. (Passifloraceae). Workers bore entrances into the horizontal hollow branches (domatia) of their host B. fistulosa, near the base of the petiole of the alternate horizontal leaves. They then ambush intruders from the domatia, close to these entrances. After perceiving the vibrations caused when an insect lands on a leaf, they rush to it and sting and generally spreadeagle the insect (only small caterpillars are mastered by single workers). Among the insects likely to defoliate B. fistulosa, adult leaf beetles and large katydids were taken as prey and cut up ; single workers then retrieved some pieces, whereas other workers imbibed the prey’s haemolymph. Other insects known to defoliate this plant, if unable to escape, were killed and discarded. Small Acrea zetes L. caterpillars were stung and then discarded by single workers ; whereas locusts of different sizes were mastered by groups of workers that stung and spreadeagled them before discarding them (although a part of their haemolymph was imbibed). More workers were involved and more time was necessary to master insects taken as prey than those attacked and discarded. Consequently, the protection T. aethiops workers provide to their host B. fistulosa from defoliating insects results from predation, but more often from a type of aggressiveness wherein insects are killed and then discarded.

P-33. Foucaud J, Fournier D, Orivel J, Delabie JHC, Loiseau A, Le Breton J, Kergoat GJ & Estoup A. 2007. Sex and clonality in the little fire ant. Molecular Biology and Evolution, 24 : 2465-2473.

Abstract

Reproduction systems are controlling the creation of new genetic variants as well as how natural selection can operate on these variants. Therefore, they had historically been one of the main foci of evolutionary biology studies. The little fire ant, Wasmannia auropunctata, has been found to display an extraordinary reproduction system, in which both males and female queens are produced clonally. So far, native sexual populations of W. auropunctata have not been identified. Our goals were to identify such sexual populations and investigate the origins of female parthenogenesis and male clonality. Using mitochondrial DNA and microsatellite markers in 17 native populations, we found that traditional sexual populations occurred in W. auropunctata and are likely the recent source of neighboring clonal populations. Queen parthenogenesis has probably evolved several times through mutational events. Male clonality is tightly linked to queen parthenogenesis and thus appears to be female controlled. Its origin could be accounted for by 2 mutually exclusive hypotheses : either by the expected coevolution of the 2 sexes (i.e., a variant of the maternal genome elimination hypothesis) or by a shared mechanistic origin (i.e., by the production of anucleate ovules by parthenogenetic queens). Our results also show that W. auropunctata males and females do not form separate evolutionary units and are unlikely to be engaged in an all-out battle of sexes. This work opens up new perspectives for studies on the adaptive significance and evolutionary stability of mixed sexual and clonal reproduction systems in living organisms.

P-32. Tindo M, Kenne M, Orivel J & Dejean A. 2007. Morphological and physiological correlates of the colony foundation mode and reproductive role differentiation in Belonogaster juncea juncea (Vespidae, Polistinae). Insectes Sociaux, 54 : 154-157.

Abstract

A study on the reproductive status of Belonogaster juncea juncea individuals was conducted in Cameroon on 21 pre- and 15 post-emergence colonies. We compared the females\’ size and ovarian development, and verified if they were inseminated or not. Dominant females were inseminated, had well developed ovaries, and were the largest individuals in pre-emergence colonies ; in post-emergence colonies their size did not differ significantly from that of non-dominant females. Most subordinate females of both pre- and post-emergence colonies had thread-like ovaries, but a few had well developed ovaries. In pre-emergence colonies 13 subordinates had thread-like ovaries and several yellow bodies indicating that they had already laid eggs. We deduced that subordinates with well developed ovaries joined the foundations shortly before our study, while those with several yellow bodies had arrived some time before and their ovaries had regressed. At the end of the post-emergence phase appear non-dominant females with well developed ovaries. They are the future foundresses. Some females can disperse just after emergence and join a new foundation without mating. Nevertheless, most co-foundresses were inseminated when they joined the foundations, and so had the potential to reproduce, negating the hypothesis of swarm founding in B. j. juncea.

P-31. Groc S, Delabie JHC, Céréghino R, Orivel J, Jaladeau F, Grangier J, Mariano CSF & Dejean A. 2007. Ant species diversity in the Grands Causses (Aveyron, France) : in search of sampling methods adapted to temperate climates. Comptes Rendus Biologies, 330 : 913-922.

Abstract

This study aimed at showing the applicability of using a combination of four sampling methods (i.e., Winkler extractors, pitfall traps, baiting and manual collection), something most often conducted in the tropics, to create an inventory of ant species diversity in temperate environments. We recorded a total of 33 ant species in the Grands Causses by comparing three vegetal formations : a steppic lawn (‘causse’ sensu stricto), which was the most species-rich (29 species), followed by an oak grove (22 species) and a pine forest (17 species). No sampling method alone is efficient enough to provide an adequate sampling, but their combination permits one to make a suitable inventory of the myrmecofauna and to obtain information on the ecology of these ant species.

P-30. Le Breton J, Dejean A, Snelling G & Orivel, J. 2007. Specialized predation on Wasmannia auropunctata by the army ant Neivamyrmex compressinodis. Journal of Applied Entomology, 131 : 740-743.

Abstract

We report here the first case of an efficient and specialized predator of the invasive ant species Wasmannia auropunctata : the army ant Neivamyrmex compressinodis. Our results are based on a study that we conducted in French Guiana, a part of the Wasmannia\’s native range. When N. compressinodis workers attacked W. auropunctata nests, the assaulted workers panicked and left the nests, some of them carrying brood. Nevertheless, during its raids on W. auropunctata, N. compressinodis was able to capture nearly all of the W. auropunctata brood and winged sexuals, whereas none of the attacks by N. compressinodis on other sympatric ant species were successful. Laboratory experiments revealed that the workers of eight compared sympatric species attacked the N. compressinodis individuals and that N. compressinodis workers accepted W. auropunctata brood as well as that of most of the tested species, showing that its specificity probably depends on the reaction of the W. auropunctata workers.

P-29. Gibernau M, Orivel J, Delabie JHC, Barabé D & Dejean A. 2007. An asymmetrical relationship between an arboreal ponerine ant and a trash-basket epiphyte (Araceae). Biological Journal of the Linnean Society, 91 : 341-346.

Abstract

The relationship between ants and Philodendron insigne, a trash-basket epiphyte abundant along streams, was studied in French Guiana. Only a few (3%) of the young plants sheltered ants, whereas 90% of the mature individuals did. The most frequent associate was Odontomachus hastatus (Fabricius), an arboreal ponerine ant, and its nests were almost entirely (94.4%) located in P. insigne root clusters. Experimental choice tests conducted on O. hastatus workers confirmed their preference for P. insigne. We propose that the interactions between P. insigne and ants may be intermediate between non-obligatory, reward-based interactions and obligatory, specific ant–myrmecophyte interactions because (1) almost all mature P. insigne individuals are associated with ants ; (2) O. hastatus is the most frequent when diverse ants nest in its root clusters ; (3) ants colonize mature P. insigne, but rarely young individuals ; (4) ants, particularly O. hastatus, protect the foliage of their host ; and (5) at least one ant species, O. hastatus, prefers P. insigne over other host plants. The latter relationship is asymmetrical because P. insigne is inhabited by diverse ants whereas O. hastatus nests almost exclusively in P. insigne.

P-28. Vantaux A, Dejean A, Dor A & Orivel J. 2007. Parasitism versus mutualism in the ant-garden parabiosis between Camponotus femoratus and Crematogaster levior. Insectes Sociaux, 54 : 95-99.

Abstract

Ant-gardens represent a special type of association between ants and epiphytes. Frequently, two ant species can share the same nest in a phenomenon known as \"parabiosis\", but the exact nature (i.e., mutualistic or parasitic) of this interaction is the subject of debate. We thus attempted to clarify the mutual costs and benefits for each partner (ants and plants) in the Crematogaster levior/ Camponotus femoratus ant-garden parabiosis. The ants\’ response to experimental foliar damage to the epiphytes and to the host tree as well as their behavior and interactions during prey capture were investigated to see if the purported parasitic status of Cr. levior could be demonstrated in either the ant-ant or in the ant-plant interactions. The results show that both species take part in protecting the epiphytes, refuting the role of Cr. levior as a parasite of the ant-garden mutualism. During capture of large prey Ca. femoratus took advantage from the ability of Cr. levior to discover prey ; by following Cr. levior trails Ca. femoratus workers discover the prey in turn and usurp them during agonistic interactions. Nevertheless, the trade-off between the costs and benefits of this association seems then to be favorable to both species because it is known that Cr. levior benefits from Ca. femoratus building the common carton nests and furnishing protection from vertebrates. Consequently, parabiosis can then be defined as the only mutualistic association existing between ant species, at least in ant-gardens.

P-27. Le Breton J, Orivel J, Chazeau J & Dejean A. 2007. Unadapted behaviour of native dominant ant species during the colonization of an aggressive invasive ant. Ecological Research, 22 : 107-114.

Abstract

Among the factors driving the invasive success of non-indigenous species, the ‘‘escape opportunity’’ or ‘‘enemy release’’ hypothesis argues that an invader’s success may result partly from less resistance from the new competitors found in its introduced range. In this study, we examined competitive interactions between the little fire ant Wasmannia auropunctata (Roger) and ant species of the genus Pheidole in places where both are native (French Guiana) and in places where only species of Pheidole are native (New Caledonia). The experimental introduction of W. auropunctata at food resources monopolized by the Pheidole species induced the recruitment of major workers only for the Guianian Pheidole species, which were very effective at killing Wasmannia competitors. In contrast, an overall decrease in the number of Pheidole workers and no recruitment of major workers were observed for the New Caledonian species, although the latter were the only ones able to kill the Wasmannia workers. These results emphasize the inappropriate response of native dominant New Caledonian species to W. auropunctata and, thus, the importance of enemy recognition and specification in the organization of ant communities. This factor could explain how invasive animal species, particularly ants, may be able to successfully invade species-rich communities.

P-26. Grangier J, Le Breton J, Dejean A & Orivel J. 2007. Coexistence between Cyphomyrmex ants and dominant populations of Wasmannia auropunctata. Behavioural Processes 74 : 93–96.

Abstract

The little fire ant Wasmannia auropunctata is able to develop highly dominant populations in disturbed areas of its native range, with a resulting negative impact on ant diversity. We report here on the tolerance of such populations towards several fungus-growing ants of the genus Cyphomyrmex (rimosus complex) in French Guiana. This tolerance is surprising given the usually high interspecific aggressiveness of W. auropunctata when dominant. In order to understand the mechanisms behind such proximity, aggressiveness tests were performed between workers of the different species. These behavioural assays revealed a great passivity in Cyphomyrmex workers during confrontations with W. auropunctata workers. We also found that the aggressiveness between W. auropunctata and two Cyphomyrmex species was more intense between distant nests than between adjacent ones. This dear–enemy phenomenon may result from a process of habituation contributing to the ants’ ability to coexist over the long term.

P-25. Denis D, Orivel J, Hora RR, Chameron S & Fresneau D. 2006. First record of polydomy in a monogynous ponerine ant : a means to allow emigration between Pachycondyla goeldii nests. Journal of Insect Behavior, 19 : 279-291.

Abstract

The ponerine ant Pachycondyla goeldii is a monogynous (i.e. one queen per colony) arboreal species that colonizes pioneer areas. Founding queens and first generation workers initiate their own ant garden by building a cardboard-like structure into which epiphyte seeds are integrated. Following the growth of the epiphyte, the colony establishes its nest within the root system. This particular nest-building behavior is crucial in an environment where suitable nest sites are rare. Nevertheless, the slow growing process of ant gardens does not allow this species to readily evacuate and find another refuge in the advent of an attack by a predator or worsening climatic conditions. Previous field studies of P. goeldii were performed after forest destruction and subsequent colonization by P. goeldii. As a result, the colonies studied where relatively young and monodomous (i.e. one nest per colony). Our study of nest composition, worker exchanges between ant gardens in the field, and dyadic encounters shows that mature colonies of P. goeldii are polydomous (i.e. multiple nests per colony). In ants, the association of polydomy with monogyny has infrequently been reported. To our knowledge, P. goeldii represents the first record of a Ponerinae exhibiting both these particular characteristics. Our field and laboratory experiments suggest that polydomy is adaptively advantageous in coping with the microclimatic instability of pioneer areas by providing colonies with easily accessible nests.

P-24. Roisin Y, Dejean A, Orivel J, Corbara B, Samaniego M & Leponce M. 2006. Vertical stratification of the termite assemblage in a neotropical rainforest. Oecologia, 149 : 301-311.

Abstract

The importance of termites as decomposers in tropical forests has long been recognized. Studies on the richness and diversity of termite species and their ecological function have flourished in more recent times, but these have been mostly conducted in a thin stratum within a standing man’s reach. Our aims were to evaluate the specific richness and composition of the termite assemblage in the canopy of a tropical rainforest and to determine its originality with respect to the sympatric ground-level fauna. We conducted systematic searches for canopy termites, together with con- ventional sampling of the sympatric ground-level fauna, in the San Lorenzo forest, Panama. We hypothesized that (1) the canopy accommodates two categories of wood-feeding termites (long-distance foragers and small-colony ‘‘one-piece’’ species) and possibly soil-feeders in suspended soil-like habitats ; (2) due to the abundance of soil-feeders, the overall diversity of the ground fauna is higher than that of the canopy ; (3) differences in microclimate and resource accessibility favour vertical stratification among wood-feeders. Sixty-three canopy samples yielded ten species of termites, all wood-feeders. Five of these were not found at ground level, although a total of 243 ground samples were collected, representing 29 species. In addition to long-distance foragers (Microcerotermes and Nasutitermes spp.) and small-colony termites (mostly Kalotermitidae), the canopy fauna included Termes hispaniolae, a wood-feeding Termitidae from an allegedly soil-feeding genus, living in large dead branches. Soil-feeders were absent from the canopy, probably because large epiphytes were scarce. As predicted, the ground fauna was much richer than that of the canopy, but the species richness of both habitats was similar when only wood-feeders were considered. Vertical stratification was strongly marked among wood-feeders, as all common species, apart from the arboreal-nesting Microcerotermes arboreus, could unequivocally be assigned to either a ground or a canopy group. The canopy, therefore, contributes significantly to the total species richness of the termite assemblage, and the diversity, abundance and ecological importance of canopy termites in tropical rainforests may be higher than previously recognized.

P-23. Kenne M, Mony R, Tindo M, Kamaha LC, Orivel J & Dejean A. 2005. The predatory behaviour of a tramp ant species in its native range. Comptes Rendus Biologies, 325 : 1025-1030.

Abstract

Workers of the pest ant Paratrechina longicornis participate in a type of group hunting. Each individual forages with its long antennae wide open and moves quickly (6.3 cm/s) along an erratic path surrounded by nestmates behaving in the same way and within range of a recruiting pheromone. They detect prey by contact with successful workers singly capturing and retrieving small prey and seizing larger ones by an appendage. Then they recruit nestmates at short-range ; all together they spread-eagle the prey and retrieve them whole.

P-22. Fournier D, Estoup A, Orivel J, Foucaud J, Jourdan H, Le Breton J & Keller L. 2005. Clonal reproduction by males and females in the little fire ant. Nature, 435 : 1230-1234.

Abstract

Sexual reproduction can lead to major conflicts between sexes and within genomes. Here we report an extreme case of such conflicts in the little fire ant Wasmannia auropunctata. We found that sterile workers are produced by normal sexual reproduction, whereas daughter queens are invariably clonally produced. Because males usually develop from unfertilized maternal eggs in ants and other haplodiploid species, they normally achieve direct fitness only through diploid female offspring. Hence, although the clonal production of queens increases the queen’s relatedness to reproductive daughters, it potentially reduces male reproductive success to zero. In an apparent response to this conflict between sexes, genetic analyses reveal that males reproduce clonally, most likely by eliminating the maternal half of the genome in diploid eggs. As a result, all sons have nuclear genomes identical to those of their father. The obligate clonal production of males and queens from individuals of the same sex effectively results in a complete separation of the male and female gene pools. These findings show that the haplodiploid sex-determination system provides grounds for the evolution of extraordinary genetic systems and new types of sexual conflict.

P-21. Dejean A, Solano PJ, Ayrolles J, Corbara B & Orivel J. 2005. Arboreal ants build traps to capture prey. Nature, 434 : 973.

Abstract

To meet their need for nitrogen in the restricted foraging environment provided by their host plants, some arboreal ants deploy group ambush tactics in order to capture flying and jumping prey that might otherwise escape. Here we show that the ant Allomerus decemarticulatus uses hair from the host plant’s stem, which it cuts and binds together with a purpose-grown fungal mycelium, to build a spongy ‘galleried’ platform for trapping much larger insects. Ants beneath the platform reach through the holes and immobilize the prey, which is then stretched, transported and carved up by a swarm of nestmates. To our knowledge, the collective creation of a trap as a predatory strategy has not been described before in ants.

P-20. Fournier D, Foucaud J, Loiseau A, Cross-Arteil S, Jourdan H, Orivel J, Le Breton J, Chazeau J, Dejean A, Keller L & Estoup A. 2005. Characterization and PCR multiplexing of polymorphic microsatellite loci for the invasive ant Wasmannia auropunctata. Molecular Ecology Notes, 5 : 239-242.

Abstract

Highly polymorphic genetic markers provide a useful tool for estimating genetic parameters in studies of the evolution of sociality in insects. We isolated and characterized 12 polymorphic microsatellite loci in the invasive ant, Wasmannia auropunctata, and described experimental conditions for PCR (polymerase chain reaction) multiplexing and simultaneously genotyping these loci in two sets of five and seven markers. The number of alleles per locus ranged from two to 14 and the observed heterozygosity ranged from 0.233 to 0.967. Moreover, results of cross-species amplification tests are reported in three other species of Wasmannia and in two species of the genus Allomerus.

P-19. Dejean A, Le Breton J, Suzzoni JP, Orivel J & Saux-Moreau C. 2005. Influence of interspecific competition on the recruitment behavior and liquid food transport in the tramp ant species Pheidole megacephala. Naturwissenschaften, 92 : 324-327.

Abstract

This study was conducted on the reactions of Pheidole megacephala scouts when finding liquid food sources situated on territories marked by competing dominant ant species or on unmarked, control areas to see if the number of recruited nestmates is affected and if soldiers behave in ways adapted to the situation. We show that scouts recruit more nestmates, particularly soldiers, on marked rather than on unmarked areas. This recruitment allows P. megacephala to organize the defence and rapid depletion of these food sources prior to any contact with competitors. Soldiers can carry liquid foods both (1) in their crops like other Myrmicinae and (2), in a new finding concerning myrmicine ants, under their heads and thoraxes like certain poneromorph genera because the droplets adhere through surface tension strengths. Later, the liquids stored in the crop are distributed to nestmates through regurgitations during trophallaxis and the external droplets are distributed through “social buckets”, or the mode of liquid food transfer common in poneromorphs. Their flexibility to use or not use the latter technique, based on the situation, corroborates other reports that Pheidole soldiers have a relatively large behavioral repertoire.

P-18. Le Breton J, Jourdan H, Chazeau J, Orivel J & Dejean A. 2005. Niche opportunity and ant invasion : the case of Wasmannia auropunctata in a New Caledonian rain forest. Journal of Tropical Ecology, 21 : 93-98.

Abstract

Due to the unbalanced distribution of their fauna and flora, which leads to the creation of a niche opportunities, it is generally accepted that island communities offer weak biotic resistance to biological invasion. In order to empirically test this statement, we compared resource use by ants in the understorey of an undisturbed New Caledonian rain forest recently invaded by the little fire ant, Wasmannia auropunctata. We tested the exploitation of : (1) food sources by placing baits on all trees with trunks greater than 5 cm in diameter ; and (2) nesting sites on two tree species likely to shelter ant colonies. In non-invaded areas, the native ants occupied only 44.6% of the baits after 2 h of exposure, while in invaded areas all the baits were occupied by numerous W. auropunctata workers. Similarly, in non-invaded areas only 48.9% of Meryta coriacea (Araliaceae) trees and 64.5% of Basselinia pancheri (Arecaceae) sheltered ants, while in invaded areas W. auropunctata nested in 92.6–98.3% of these trees. Also, workers attended native Margarodidae (Hemiptera) for which they promoted the development of populations significantly larger than those attended by native ants. Thus native ants appear unable to efficiently exploit and defend several of the available food sources and nesting sites, providing a niche opportunity for an invader like W. auropunctata.

P-17. Dejean A, Quilichini A, Delabie JHC, Orivel J, Corbara B & Gibernau M. 2004. Influence of its associated ant species on the life history of the myrmecophyte Cordia nodosa in French Guiana. Journal of Tropical Ecology, 20 : 701-704.

Abstract

Variation in the ant species associated with myrmecophytes has been noted at both the regional and local levels, with plant distribution generally wider than that of the ants. This is the case for Cordia nodosa Lamark (Boraginaceae, subfamily Ehretioideae) whose most frequent associate ant species in Peru are Allomerus demararae (Wheeler) and Azteca spp. , while Azteca sp.1 and Allomerus octoarticulatus are the most frequent in Amazonian Brazil and French Guiana, respectively. We hypothesised that differences in the ant species associated with C. nodosa individuals from two geographical areas subsequently affect plant growth and reproduction. We therefore sought to verify if all the ant species associated with C. nodosa are able to open the domatia, if they protect their plants against herbivores, and if the plants produce fruit.

P-16. Orivel J, Servigne P, Cerdan P, Dejean A & Corbara B. 2004. The ladybird Thalassa saginata, an obligatory myrmecophile of Dolichoderus bidens ant colonies. Naturwissenschaften, 91 : 97-100.

Abstract

The larvae and pupae of the ladybird Thalassa saginata develop inside colonies of the dolichoderine ant Dolichoderus bidens. This association is the first specific and obligatory relationship recorded between ants and ladybirds. The ants provide shelter and protection to the larvae but the diet of the latter remains unclear. The integration of T. saginata larvae into the ant colonies is achieved by mimicking the cuticular patterns of the ants’ brood. Moreover, the larvae secrete substances from their hairs and anal gland that are likely to enhance their attractiveness.

P-15. Dejean A, Gibernau M, Lauga J & Orivel J. 2003. Coccinellid learning during capture of alternative prey. Journal of Insect Behavior, 16 : 859-864.

Abstract

Most coccinellid beetles are specialized predators, with a mixed diet composed of “essential prey” capable of supporting larval development and adult reproduction and “alternative prey” that only enable adults to sur- vive when essential prey are lacking. The larvae of the coccinellid Anisolemnia tetrasticta (Fairmaire), specialized in the capture of nymphs of Libyaspis sp. (Heteroptera ; Plataspidae), always detect prey by contact. In response, the Libyaspis nymphs cower, so that the margins of their laterally hypertrophied tergites come into contact with the substrate. These morphological and behavioral defenses are foiled by morphological and behavioral adaptations of the coccinellid, as the larvae slide their hypertrophied forelegs under the nymphs, lift them, and bite them on ven- tral surfaces. Anisolemnia larvae occasionally prey on another plataspid, Caternaultiella rugosa (Schouteden), when during periods of proliferation, some nymphs develop outside the pavilions where they are generally attended by ants. The Caternaultiella nymphs, devoid of morphological defenses, try to escape upon contact with the ladybird larvae that adopt the previously described behavior, or directly grasp then bite them, showing a behavioral plasticity when confronted with this alternative prey. We hypothesize that this behavioral plasticity could be coupled with learning, with a tendency for the larvae to display the sequence “grasp then bite” the Caternaultiella nymphs more frequently after several encounters.

P-14. Kenne M, Djiéto-Lordon C, Orivel J, Mony R, Durand JL & Dejean A. 2003. Influence of insecticide treatments on ant-hemiptera associations in tropical plantations. Journal of Economic Entomology, 96 : 251-257.

Abstract

In this survey conducted in southern Cameroon, we compared ant-Hemiptera associations on plantations treated with insecticides, on plantations 2 years after insecticide treatments ceased, and on control lots that never received insecticide treatments. By eliminating arboreal-nesting ants, insecticides favored the presence of “ecologically dominant” ground-nesting, arboreal-foraging species that occupied the tree crowns. The reinstallation of arboreal ants was slow as 2 yr after insecticide treatment ceased differences with the control lots were significant. This intermediary period also illustrated that arboreal ants can found and develop colonies on trees occupied by ground-nesting species. Certain arboreal species were more frequent during this intermediary period than on the control lots, showing that the period of installation in the trees was followed by competition between arboreal ants. We confirm that ground-nesting ants tend a wide range of hemipteran families, including well known agricultural pests, whereas arboreal ants, particularly dominant species, were mostly associated with Coccidae and Stictococcidae that do not pose problems to the supporting trees. A tree effect was also noted for both ant and hemipteran distribution. We concluded that because of insecticide use, ground-nesting ants pose problems through their associated Hemiptera. On the contrary, dominant arboreal ants, strong predators, benefit their supporting trees by excluding ground-nesting species and tending mostly nonpest Hemiptera. Nevertheless, certain of them, carpenter species or species likely to tend Pseudococcidae, have to be eliminated through integrated management.

P-13. Dejean A, Durou S, Olmsted I & Snelling RR & Orivel J. 2003. Nest site selection by ants in a flooded Mexican mangrove, with special reference to the epiphytic orchid Myrmecophila christinae. Journal of Tropical Ecology, 19 : 325-330.

Abstract

The distribution of the arboreal ant community plus a termite species of the genus Nasutitermes was inventoried on 938 red mangrove, Rhizophora mangle L., trees in a completely flooded mangrove forest of the Sian Ka’an Biosphere Reserve, Quintana Roo, Mexico. Colonies sheltered in dry hollow branches of the trees and the pseudobulbs of the epiphytic orchid, Myrmecophila christinae. Two size classes of dry hollow tree branches were categorized in order to test differences in ant distribution. As some trees remained unoccupied by either an ant or a termite colony, we deduced that the competition for nesting sites was low. Differences in the composition of the ant community corresponded to the nature of the shelters (i.e. diameter of the hollow branches or orchid pseudobulbs). The ant fauna was richer in the large dry hollow branches of R. mangle than in the smaller ones, with certain ant species belonging to the subfamilies Ponerinae and Formicinae being significantly more frequent in the large dry hollow branches than in the small ones. Cephalotes and Pseudomyrmex were the most frequent ant genera inhabiting the dry branches of R. mangle, while Dolichoderus bispinosus was the most frequent ant species inhabiting the orchid pseudobulbs. Arboreal Nasutitermes sp. selected mostly the orchid pseudobulbs and thus indirectly interfered with ant nest-site selection. Our results highlight niche differentiation through the selection of nest sites among different types of shelter.

P-12. Dejean A, Suzzoni JP, Schatz B & Orivel J. 2002. Territorial aggressiveness or predation : two possible origins of snapping in the ant Plectroctena minor. Comptes Rendus Biologies, 325 : 819-825.

Abstract

Plectroctena minor workers have long mandibles that can snap and deliver a sharp blow to intruders or prey, stunning or killing them. Encounters between homocolonial P. minor workers separated for 24 h or 15 days never resulted in snapping, while this behaviour was always noted during encounters between heterocolonial workers on neutral arenas or on the territory of a colony. In the latter case, only the aliens, that generally tried to escape, were snapped at. Snapping also occurred during encounters with workers belonging to sympatric ponerine species. During predation, the percentages of snapping varied according to prey nature, suggesting prey discrimination. Termite soldiers were always snapped at, while other prey were more often snapped close to rather than far from the nest entrances, indicating an intermingling of territorial aggressiveness and predatory behaviour. We discuss the adaptive value of snapping for hunting in galleries.

P-11. Dejean A, Orivel J & Gibernau M. 2002. Specialized predation on plataspid heteropterans in a coccinellid beetle : adaptative behavior and responses of prey attended or not by ants. Behavioral Ecology, 13 : 154-159.

Abstract

Two plataspid hemipteran species proliferated on Bridelia micrantha (Euphorbiaceae). Colonies of Libyaspis sp., never attended by ants, developed on branches, while Caternaultiella rugosa lived at the base of the trunks, mostly in association with Camponotus brutus that attends them in carton shelters. Both plataspid species are prey of the coccinellid beetle Anisolemnia tetrasticta, whose larvae always detected them by contact. When attacked the Libyaspis nymphs cowered, so that the hypertrophied lateral sides of their tergits made contact with the substrate, but the ladybirds slid their long forelegs under these nymphs, lifted them, and bit them on the ventral face. The Caternaultiella nymphs, which do not have hypertrophied extremities of the tergits, tried to escape at contact with the ladybirds, but were rarely successful. To capture them, the ladybirds either adopted the previous behavior or directly grasped then bit them. We noted a graded aggressiveness in the ants toward the ladybirds according to the situation : no aggressiveness on the tree branches ; stopping the ladybirds that approached the shelters where the ants attended Caternaultiella ; and full attack of ladybirds that tried to capture Caternaultiella nymphs situated outside shelters. The latter behavior can emit an alarm pheromone that triggers the dispersion of their congeners while attracting attending C. brutus workers. Naive workers are not attracted, so we deduce that this behavior is the result of a kind of learning.
behaviour. We discuss the adaptive value of snapping for hunting in galleries.

P-10. Djiéto-Lordon C, Orivel J, & Dejean A. 2001. Consuming large prey on the spot : the case of the arboreal foraging ponerine ant Platythyrea modesta (Hymenoptera : Formicidæ). Insectes Sociaux, 48 : 324-326.

Abstract

In Platythyrea modesta, an arboreal foraging ponerine ant, single workers mastered large prey, but were unable to retrieve them. They therefore recruited nestmates that either carved up the prey on the spot, and then solitarily retrieved pieces of prey, or consumed a part of the prey directly. Nevertheless, in most situations entire prey were consumed on the spot by recruited workers that, in certain cases, even transported larvae from the nest to the prey. In nature, the latter behavior resembles emigration. Because the colonies of P. modesta have frequently been observed when emigrating, we have compared this behavior to that of nomadic ponerine species.

P-9. Hossaert-McKey M, Orivel J, Labeyrie E, Pascal L. Delabie J & Dejean A. 2001. Differential associations with ants of three co-occurring extrafloral nectary-bearing plants. Ecoscience, 8 : 325-335.

Abstract

In contrast to many myrmecophytes, which shelter ants in hollowed structures called domatia, plants bearing extrafloral nectaries do not have specific relationships with certain ant species. However, we hypothesized that different plants might be associated with different assemblages of ants. We studied three pioneer plant species from French Guiana : Passiflora glandulosa, Passiflora coccinea (Passifloraceae) and Mimosa myriadena (Mimosaceae) that occur together in the same habitat. The guild of ants associated with each of these plants was different from the overall ant community in the study area. Ant assemblages varied among plant species and, for a given plant species, from day to night. Certain ant species frequent in the study area were rare or even absent on these plants, even species known to be very aggressive at the interspecific level, such as Wasmannia auropunctata. While territoriality between ant species probably plays some role in determining distributions across plants, differential plant attractiveness to the workers also seems to be an important factor. Our large sample size, plus the fact that these plants develop in patches in which stems are frequently in contact, suggested that a certain selectivity occurs for plant choice by ant workers.

P-8. Orivel J, Malherbe MC & Dejean A. 2001. Relationships between pretarsus morphology and arboreal life in ponerine ants of the genus Pachycondyla (Formicidæ : Ponerinæ). Annals of the Entomological Society of America, 94 : 449-456.

Abstract

Morphological traits of the pretarsa, especially the tarsal claws and arolia, of 15 arboreal or ground-dwelling species of the genus Pachycondyla demonstrate that two types of morphologies exist. All of the arboreal and three of the ground-dwelling species have a well-developed arolium in the form of an adhesive pad, whereas the others do not. Moreover, the tarsal claws are spread and horn-shaped in the species of the first group, whereas they are straight and relatively close together in the species without the adhesive pad. The ability to walk upside down is strictly correlated to the presence of the pad. If a large adhesive pad cannot be considered as a morphological adaptation to arboreal life, it, at least, constitutes an indispensable characteristic for the advent of arboreal behavior.

P-7. Orivel J, Redeker V, Le Caer JP, Krier F, Revol-Junelles AM, Longeon A, Chaffotte A, Dejean A & Rossier J. 2001. Ponericins, new antibacterial and insecticidal peptides from the venom of the ant, Pachycondyla goeldii. Journal of Biological Chemistry, 276 : 17823-17829.

Abstract

The antimicrobial, insecticidal, and hemolytic properties of peptides isolated from the venom of the predatory ant Pachycondyla goeldii, a member of the subfamily Ponerinae, were investigated. Fifteen novel peptides, named ponericins, exhibiting antibacterial and insecticidal properties were purified, and their amino acid sequences were characterized. According to their primary structure similarities, they can be classified into three families : ponericin G, W, and L. Ponericins share high sequence similarities with known peptides : ponericins G with cecropin-like peptides, ponericins W with gaegurins and melittin, and ponericins L with dermaseptins. Ten peptides were synthesized for further analysis. Their antimicrobial activities against Gram-positive and Gram-negative bacteria strains were analyzed together with their insecticidal activities against cricket larvae and their hemolytic activities. Interestingly, within each of the three families, several peptides present differences in their biological activities. The comparison of the structural features of ponericins with those of well-studied peptides suggests that the ponericins may adopt an amphipathic alpha-helical structure in polar environments, such as cell membranes. In the venom, the estimated peptide concentrations appear to be compatible with an antibacterial activity in vivo. This suggests that in the ant colony, the peptides exhibit a defensive role against microbial pathogens arising from prey introduction and/or ingestion.

P-6. Orivel J & Dejean A. 2001. Comparative effect of the venoms of ants of the genus Pachycondyla (Hymenoptera : Ponerinæ). Toxicon, 39 : 195-201.

Abstract

The venoms of 12 Pachycondyla ant species, all generalist predators, were compared for their paralytic and lethal effects during prey capture of the cricket, Acheta domesticus. The observed values covered a wide range that seems surprising when considering the close phylogenetic relatedness of the species. Although employed for different purposes, these venoms had the same type of physiological effect. They caused a rapid, dose-dependent and reversible paralysis, followed by a second slow-acting paralysis which was permanent when complete and led to death in less than 4 days. This finding suggests the existence of similar toxins and of both neurotoxins and histolytic compounds as necrosis were often observed in dead animals. Comparisons based on the nesting habitats of the species highlighted significant differences in paralysis after 2 h and lethality with arboreal species\’ venoms more efficacious than those of ground-dwelling species, thanks to their higher potency and their rather fast-acting effect. Such a tendency may be considered as an adaptation to arboreal life as the possibilities of escape for the prey are more numerous than on the ground or in the leaf litter.

P-5. Orivel J & Dejean A. 2000. Myrmecophily in Hesperiidæ : the case of Vettius tertianus in ant gardens. Comptes Rendus de l’Académie des Sciences, série III, 323 : 705-715.

Abstract

The larvae of the hesperiid butterfly Vettius tertianus develop by eating the leaves of Aechmea mertensii, a bromeliad epiphyte restricted to ant gardens. The relationships between ants and V. tertianus larvae highlight the preferential association of the caterpillars with Pachycondyla goeldii (Ponerinae), an ant-garden initiator. The oviposition strategy of V. tertianus may thus imply the identification of the inhabiting ant species and not only the identification of the host plant. The caterpillars neither provide secretions to the ants, nor possess defensive devices (i.e. hairs or appendices) against ants. Their activity rhythm does not isolate them from foraging workers of P. goeldii and their shelters are also attainable by the ants. Moreover, as the cuticular lipid profiles of V. tertianus larvae are clearly different from those of the ants and also from the leaf-surface of A. mertensii, acceptance is not due to mimicry between larvae and plants or ants. However, the caterpillars deposit, on the leaf they eat, silk containing a mixture of substances very similar to those found on their own cuticle. No interaction with ants was recorded during observations, even though the ant gardens were patrolled by numerous P. goeldii individuals during their activity period. But when confronted with the caterpillar, none of the tested ant species reacted aggressively. These results suggest the existence of compounds, other than cuticular lipids, responsible for the absence of aggressiveness in the ants. The case of V. tertianus is relatively new as myrmecophily within Hesperiidae has been described only once. Moreover, it preferentially involves a member of the Ponerinae, a subfamily in which interactions with other arthropods are exceptional.

P-4. Dejean A, Bourgoin T & Orivel J. 2000. Ant defense of Euphyonarthex phyllostoma (Homoptera : Tettigometridæ) during trophobiotic associations. Biotropica, 32 : 112-119.

Abstract

During a five-year field study, we made observations and conducted experiments to demonstrate unequivocally that Euphyonarthex phyllostoma (Fulgoromorpha : Tettigometridae) is a myrmecophile. Isolated adults and colonies always were found in association with ants. Colonies were associated only with Camponotus brutus or C. acvapimensis (Formicinae), whereas isolated adults were attended by ants belonging to several species of Formicinae, Dolichoderinae, and Myrmicinae. The size of the planthopper colonies reached higher levels when attended by C. brutus than by C. acvapimensis. Experiments using ant exclusion showed that both ant species protected egg masses against parasitic wasps, but egg masses were less parasitized on trees occupied by C. brutus than on those occupied by C. acvapimensis (P = 0.0052). The production of egg masses by female hoppers was recorded only when C. brutus, C. acvapimensis, or the myrmicine ant Myrmicaria opaciventris attended the hopper. In both former cases, the presence of ants influenced the aggregation of the nymphs as they dispersed when ants were excluded. The aggregation of the nymphs ensured that they were properly attended. Parental care by the females was reduced to their presence above or close to the egg masses. In fact, specialized workers of the attending ant species protected the egg masses as well as nymphs.

P-3. Orivel J & Dejean A. 1999. Selection of epiphyte seeds by ant-garden ants. Ecoscience, 6 : 51-55.

Abstract

An inventory of 501 ant gardens inhabited by Camponotus femoratus Fabr., Crematogaster limata parabiotica Forel in parabiosis or alone, and Pachycondyla goeldii Forel enabled us to record 11 epiphyte species. Each epiphyte species can be associated with any ant species, but a factorial correspondence analysis highlighted preferential associations. P. goeldii was preferentially associated with Aechmea mertensii Schult. and Anthurium gracile Rudge, whereas C. femoratus and Cr. l. parabiotica were associated with Codonanthe calcarata Miq., Peperomia macrostachya Vahl., and Philodendron spp. The carrying of diaspores by ants also varied according to ant and epiphyte species. Each ant species transported certain epiphyte diaspores rather than others and the proportions of carried diaspores corresponded to those of mature epiphytes in ant gardens. Seed attractiveness and retrieval to the nest still occur when elaiosomes are removed. They are thus not indispensable and reinforce dispersal. Ecological factors may also explain the preferential associations observed and they may intervene at different levels.

P-2. Orivel J, Dejean A & Errard C. 1998. Active role of two ponerine ants in the elaboration of ant gardens. Biotropica, 30 : 487-491.

Abstract

The objective of this study was to verify if P. goeldii and O. mayi are capable of establishing ant gardens as do certain species of Myrmicinae, Dolichoderinae, and Formicinae. To that end, we investigated the following four questions : (1) Are the workers of P. goeldii and O. mayi attracted to the seeds of various plants, in particular the epiphytes present in the ant gardens ? (2) Do they transport these seeds to their nests ? (3) Do they plant these seeds in the walls of their nests ? (4) Are these seeds capable of germinating ?

P-1. Orivel J, Errard C & Dejean A. 1997. Ant gardens : Interspecific recognition in parabiotic ant species. Behavioral Ecology and Sociobiology, 40 : 87-93.

Abstract

In French Guiana, parabiotic societies (natural mixed colonies) are frequently found in ant gardens. Crematogaster limata parabiotica (Myrmicinae), often associated with Camponotus femoratus (Formicinae), was found for the first time in parabiosis with ponerine ants : Pachycondyla goeldii and Odontomachus mayi. A detailed study of the relationships between Cr. l. parabiotica and O. mayi showed that each species is aggressive towards allospecific or conspecific individuals belonging to an- other colony, but tolerates allospecific individuals from the multi-species society. Studies of cuticular substances of the four ant species were made using gas chromatography. The results showed that each species, living alone or in parabiosis, possesses a specific chemical profile. Thus, the ants are able to recognise nestmate and non-nestmate individuals of the associated species, even though their cuticular profiles are different. The hypothesis that the nestmate allospecific profile is learned is suggested to explain this pattern of recognition.

Other publications (journals with IF < 0.5 or not indexed in ISI)

P’-21. Lauth J, Ruiz-González MX & Orivel J. 2011. New findings in insect fungiculture : Have ants developed non-food, agricultural products ? Communicative and Integrative Biology, 4:728-730.

Abstract

The interaction between Allomerus plant-ants and an ascomycete fungus growing on and strengthening their galleries is not opportunistic. We previously demonstrated that this association is highly specific as only one fungal species represented by a few haplotypes was found associated with the ants. We also discovered that the ants’ behavior revealed a major investment in manipulating and enhancing the growth of their associated fungus. We have growing evidence that this specificity is consistent with selection by the ants. Here, we discuss this selection within the framework of insect agriculture, as we believe these ants fulfill all of the prerequisites to be considered as farmers. Allomerus ants promote their symbiont’s growth, protect it from potential pathogens and select specific cultivars. Taken together, we think that the interaction between Allomerus ants and their cultivar might represent the first case of insect fungiculture used as a means of obtaining building material.

P’-20. Basset Y, Corbara B, Barrios H, Cuénoud P, Leponce M, Aberlenc H-P, Bail J, Bito D, Bridle JR, Castaño-Meneses G, Cizek L, Cornejo A, Curletti G, Delabie JHC, Dejean A, Didham RK, Dufrêne M, Fagan LL, Floren A, Frame DM, Hallé F, Hardy OJ, Hernandez A, Kitching RL, Lewinsohn TM, Lewis OT, Manumbor M, Medianero E, Missa O, Mitchell AW, Mogia M, Novotny V, Oliveira EGD, Ødegaard F, Orivel J, Ozanne CMP, Pascal O, Pinzón S, Rapp M, Ribeiro SP, Roisin Y, Roslin T, Roubik DW, Samaniego M, Schmidl J, Sørensen LL, Tishechkin A, Van Osselaer C & Winchester NN. 2007. IBISCA-Panama, a large-scale study of arthropod beta-diversity and vertical stratification in a lowland rainforest : rationale, description of study sites and field methodology. Bulletin de l\’Institut Royal des Sciences Naturelles de Belgique- Entomologie, 77 : 39-69.

Abstract

IBISCA-Panama (Investigating the BIodiversity of Soil and Canopy Arthropods, Panama module) represents a large-scale research initiative to quantify the spatial distribution of arthropod biodiversity in a Neotropical forest, using a combination of (1) international collaboration, (2) a set of common research questions, and (3) an integrated experimental design. Here, we present the rationale of the programme, describe the study sites, and outline field protocols. In the San Lorenzo Protected Area of Panama, twelve 20 x 20 m sites, all less than 2 km apart, were surveyed for plants and arthropods, from the ground to the upper canopy. Access to the canopy and its fauna was facilitated by fogging, single-rope techniques and a variety of devices such as a canopy crane, the SolVin-Bretzel canopy raft, the canopy bubble and Ikos. IBISCA-Panama represented the first attempt to combine these complementary techniques of canopy access in a large-scale investigation. Such techniques provided spatial replication during initial field work performed in September-October 2003. Temporal replication across seasons consisted of subsequent field work of varying intensity during dry, early wet and late wet periods in 2004. Arthropods were surveyed using 14 different protocols targeting the soil, litter, understorey, mid-canopy and upper canopy habitats. These protocols included : WINKLER sifting ; BERLESE-TULLGREN ; hand-collecting of galls and social insects ; fogging ; beating ; wood- rearing ; baits ; and various types of traps such as pitfall, small and large flight-interception, sticky, light, and Malaise traps. Currently, analyses of arthropod distribution in this forest concentrate on a set of 63 focal taxa representing different phylogenies and life-histories. IBISCA-Panama may be considered as a model for large-scale research programmes targeting invertebrate biodiversity. Its collaborative modus operandi can be applied to answer a variety of pressing ecological questions related to forest biodiversity, as evidenced by the recent development of further IBISCA programmes in other parts of the world.

P’-19. Dejean A, Corbara B, Orivel J & Leponce M. 2007. Rainforest canopy ants : the implications of territoriality and predatory behavior. Functional Ecosystems and Communities, 1 : 105-120.

Abstract

After first being ground-nesters and predators or scavengers, ants became arboreal with the rise of angiosperms and provided plants a biotic defense by foraging for prey on their foliage. Plants induce ants to patrol on their leaves through food rewards (e.g., extra-floral nectar and food bodies), while ants attend hemipterans for their honeydew. Most arboreal-nesting ants build their own nests, but myrmecophytes, plants that offer hollow structures that serve as nesting places to specialized “plant-ants”, illustrate the tight evolutionary bonds between ants and plants. In tree-crop plantations and in some rainforest canopies territorially-dominant arboreal ants have large colonies with large and/or polydomous nests. Their territories are defended both intra- and interspecifically, and are distributed in a mosaic pattern, creating what has become known as “arboreal ant mosaics”. They tolerate non-dominant species with smaller colonies on their territories. Arboreal ant mosaics are dynamic because ant nesting preferences differ depending on the species and the size and age of supporting trees. Because the canopy is discontinuous, arboreal-foraging ants can be found in ant mosaics ; invasive ants can affect also the structure of the mosaic. We discuss here the methods that permit us to study these mosaics. Territorially-dominant arboreal ants are good predators that use group ambushing to catch flying insects on their host tree foliage. When producing winged sexuals they also forage for prey on the ground and plunder the colonies of non-dominant species sharing their host tree. When expanding their territories, the workers of the victorious colony raid the defeated colony. Because territorially-dominant arboreal ants prey on herbivores and strongly affect their general activity, ants are frequently used as biological control agents.

P’-18. Mony R, Kenne M, Orivel J & Dejean A. 2002. Biology and ecology of pest ants of the genus Melissotarsus (Formicidae ; Myrmicinae), with special reference to tropical fruit attacks. Sociobiology, 40 : 385-402.

Abstract

We show in this study that Melissotarsus beccarii and M. weissi, two myrmicine species, are pest ants that dig galleries in the bark of trees in order to nest and attend Diaspididae (Hemiptera). Among the trees attacked figure species of economical importance such as Mangifera indica (mango tree ; Anacardiaceae), Dacryodes edulis (safoo tree), and Aucoumea klaineana (okoume ; both latter species Burseraceae). The extent of the damage is due to large polygynous colonies with a monomorphic worker caste. Indeed, we estimated that a safoo tree supported a M. beccarii colony of 1,585,000 individuals (larvae included) attending 556,000 Diaspis sp., while two mango trees supported 412,000 and 361,000 M. weissi individuals attending 405,000 and 330,000 Morganella pseudospinigera, respectively. During a survey conducted on 185 safoo and 513 mango trees we noted that most old, large trees were attacked, while young trees, apparently, were not. Bimonthly samplings of bark permitted us to note the year round presence of winged sexuals in mature M. beccarii colonies ; the periods of higher presence of females and males being globally the same. On the contrary, we noted an asynchrony in the presence of winged females and males in M. weissi, a situation probably related to a strategy favoring intercolonial mating. Although the production of females was widespread throughout the year, founding queens were mostly observed between March and June (rainy season), suggesting that during the other seasons mated females join their nests.

P’-17. Orivel J & Dejean A. 2002. Response to comments on « Relationships between pretarsus morphology and arboreal life in ponerine ants of the genus Pachycondyla (Formicidæ : Ponerinæ) » by W. Federle. Annals of the Entomological Society of America, 95 : 142.

P’-16. Orivel J & Dejean A. 2002. Ant activity rhythms in a pioneer vegetal formation of French Guiana. Sociobiology, 39 : 65-76.

Abstract

We compared the daily rhythm of activity of four sympatric ant species nesting in Guianian pioneer vegetal formations. Solenopsis saevissima was active all around the clock, but mostly at night. While Pseudomyrmex termitarius and Camponotus blandus were typically diurnal, and C. melanoticus typically nocturnal with a part of the workers transporting brood and nestmates between several nests belonging to the same colony. While S. saevissima workers attended pseudococcids and coccids at the base of different plant species, P. termitarius, C. blandus and C. melanoticus exploited the extrafloral nectaries (EFN) of Passiflora glandulosa (Passifloraceae). They frequently shared the same plant individuals. Camponotus blandus and C. melanoticus workers can also attend the same clusters of aphids sucking the sap of Graminaceae. During the day P. termitarius workers that forage singly seemed to be tolerated by the groups of C. blandus exploiting P. glandulosa EFN. The activity of C. blandus and C. melanoticus did not overlap on the Graminaceae where they attended aphids, while the C. blandus workers were obliged to leave the P. glandulosa stems that they shared with C. melanoticus between 5 and 6 p.m., due to intimidating behavior from the latter when they arrived. Certain C. melanoticus workers also installed themselves around the C. blandus nest entrances between 5 and 10 p.m. in order to prevent the workers from leaving their nest by approaching them mandibles wide open, but they let pass all the workers that returned to their nests. A similar behavior was noted between 9 p.m. and 9 a.m. around the S. saevissima nest entrances. In this case the C. melanoticus workers attacked both S. saevissima workers that tried to leave their nests or that tried to enter, strongly disturbing their traffic. The aggressive behaviors by C. melanoticus, though never injuring the aliens, can be considered as ritualized. We conclude that C. melanoticus is ecologically dominant, though S. saevissima and C. blandus are numerically dominant, while P. termitarius is a non-dominant species.

P’-15. Djiéto-Lordon C, Richard, FJ, Owona C, Orivel J & Dejean A. 2001. The predatory behavior of the dominant ant species Tetramorium aculeatum (Hymenoptera, Formicidæ). Sociobiology, 38 : 765-775.

Abstract

We studied the predatory behavior of Tetramorium aculeatum, (Formicidae : Myrmicinae), a dominant arboreal ant species that poses problems in the agricultural milieu due to its violent venom. Hunting workers that forage collectively at night detected prey by contact, seized them by an appendage or, to a lesser degree by the head or the abdomen, then pulled backward but did not sting them systematically. Only a few small prey were captured by a single worker. We argue that these workers can recruit at short-range, nestmates situated in the vicinity as the latter rapidly arrived. Each of them seized in turn a prey appendage and pulled backward. As a result, the prey were spread-eagled. Along range recruitment occurred in order to subdue large prey. Almost all kinds of prey were spread-eagled and generally cut up on the spot. The arolia in the form of adhesive pads and the horn-shaped pointed claws on the pretarsa are important in the success of prey capture (spread-eagling) and transport in an arboreal habitat. These results are compared with those known for other dominant arboreal ant species.

P’-14. Dejean A, Solano P, Orivel J, Belin-Depoux M, Cerdan P & Corbara B. 2001. The spread-eagling of prey by the obligate plant-ant Pheidole minutula (Myrmicinae) : similarities with dominant arboreal ants. Sociobiology, 38 : 675-682.

Abstract

Pheidole minutula is an arboreal ant species with minute workers (about 2mm in length) that lives in association with the myrmecophyte Maieta guianensis (Melastomataceae). The workers constantly patrol the associated plant leaves, with each leaf patrolled by several workers. The predatory behavior of this ant species was studied using termite larvae (small prey) and workers (large prey). Only a few small prey were captured by a single worker ; otherwise, we noted cooperative hunting. After detection, patrolling workers attacked the prey by seizing them by a leg, then pulling backward. In reaction the prey pulled in the opposite direction. We argue that these workers can recruit at short-range nestmates situated on the same leaf. Each new worker that arrived seized in turn a prey leg and pulled backward. As a result, the prey were spread-eagled. Long-range recruitment was used for large prey. Small and large prey were cut up on the spot or retrieved whole. We never noted the use of venom. These results are compared with those known for dominant arboreal ant species.

P’-13. Labeyrie E, Pascal L, Delabie J, Orivel J, Dejean A & Hossaert-McKey M. 2001. Protection of Passiflora glandulosa (Passifloraceæ) against herbivory : impact of ants exploiting extrafloral nectaries. Sociobiology, 38 : 317-321.

Abstract

In French Guiana we studied the protective role of four ant species on Passiflora glandulosa (Passifloracae), a liana bearing extrafloral nectaries. By ant exclusion experiments, using birdlime, we showed that stems from which ants were excluded were significantly more attacked by phytophagous insects than control stems visited by ants. Among the ant species that protected P. glandulosa, Camponotus blandus and Ca. melanoticus are ground-nesting, arboreal-foraging species that share territories, one species being diurnal, the other nocturnal. These ants visit and protect plants whose shoot tips are located on or near the ground, i.e., plants creeping on the ground and/or young individuals. The two other species of ants observed on P. glandulosa in the site, Ca. femoratus and Crematogaster limata parabiotica, are typical arboreal ants that can protect large plants climbing on trees. We conclude that it is advantageous for a liana to be able to establish associations with a range of different ant species providing continuous defense of shoot tips as they grow toward the canopy.

P’-12. Djiéto-Lordon C, Orivel J & Dejean A. 2001. Predatory behavior of the african ponerine ant Platythyrea modesta (Hymenoptera : Formicidæ). Sociobiology, 38 : 303-316.

Abstract

We compared the predatory behavior of Platythyrea modesta, one of the rare African ponerine ants with arboreal foraging habits, which is a generalist predator when confronted with prey of different types and sizes. The sequence of prey capture is similar in several ways to those of other generalist predators of the sub-family Ponerinae. The swiftness of these ant workers enables them to capture a wide variety of prey, including several arboreal insects. Prey detection was almost always by contact for small and a few mobile termite prey, while it was usually from a distance for larger and more mobile grasshoppers. After detection, the ants attacked without antennating the prey, which resulted in seizure by the thorax (for small prey), and either by an appendage or the abdomen for large prey. Small prey were rarely stung, but killed thanks to mandible pressure, while large prey were always stung. Prey retrieval was always performed by single workers, so that only small prey were retrieved whole. When compared to other ponerine ants, the predatory behavior of this species is characterized by short capture sequences without antennation and the great efficacy of the venom in quickly paralysing even large prey. This appears to be well adapted to arboreal foraging. Large prey were sometimes carved up and small pieces retrieved by single workers, but more frequently, they were eaten on the spot. The most striking behavior of this ant species is the fact that, instead of carving large prey on the spot and then retrieving the pieces, the workers recruited nestmates that fed directly on the prey.

P’-11. Dejean A, Orivel J, Corbara B, Olmsted I & Lachaud JP. 2001. Nest site selection by two polistine wasps : the influence of Acacia-Pseudomyrmex associations against predation by army ants (Hymenoptera). Sociobiology, 37 : 135-146.

Abstract

Nest site selection by two neotropical polistine wasps, Parachartergus apicalis and Polybia rejecta was studied in Quintana Roo, Mexico, to assess whether they nest in association with arboreal ants that protect them against army ants. Pa. apicalis nest mostly on Acacia occupied by the ant Pseudomyrmex ferruginea or Ps. peperi while Po. rejecta nest on these Acacia or on other trees occupied by large colonies of dolichoderine ants of the genera Azteca and Dolichoderus. Intraspecific nesting associations (nests on the same tree), also a possible anti-predator strategy, concerned only 13 out of 129 Pa. apicalis nests, whereas nesting associations were frequent and independent of the associated ant species in Po. rejecta and concerned 58 wasp nests out of 92 (significant difference with Pa. apicalis). Interspecific associations between wasps occurred only twice. The trees supporting wasp nests were grouped. We then tested the reaction of columns of Eciton burchelli, the most frequent army ant species noted, when confronted with Ps. ferruginea located on branches of Acacia. Army ants avoided Ps. ferruginea, permitting us to verify that the association with Pseudomyrmex could provide the wasp nests protection against army ants (as known for associations with arboreal Dolichoderinae).

P’-10. Dejean A, Gibernau M, Durand JL, Abehassera D & Orivel J. 2000. Pioneer plant protection against herbivory : impact of different ant species (Hymenoptera : Formicidæ) on a proliferation of the variegated locust. Sociobiology, 36 : 227-236.

Abstract

This study was conducted in order to determine the protective role of
ants on Alchornea cordifolia (Müll. Arg.), a pioneer Euphorbiaceae with
extrafloral nectaries, during a proliferation of Zonocerus variegatus (L.)
(Orthoptera ; Pyrgomorphidae). The associated ant species recorded
along river banks (typical habitat of A. cordifolia) and dirt roads
(extension of the plant species area of distribution due to human
activity) were basically the same, but the proportions between ant
species varied. For example, ground-nesting, arboreal-foraging species
were more frequent along dirt roads. The most efficacious ant species
against attacks from the locust were those using the supporting plant
leaves to build their nests (i.e., Oecophylla longinoda [Latreille],
Polyrhachis laboriosa [F. Smlth], two large Formicinae, and Tetramorium
aculeatum
[Mayr], a small, nocturnal Myrmicinae). Crematogaster
striatula
(Emery), another small myrmicine ant nesting at the bases of
trees, but foraging diurnally in their foliage, also protected the plant
(significant difference with the control lot where ants were excluded),
while Camponotus brutus (Forel), a large nocturnal Formicinae, did not
protect the plant at all. These results are discussed according to the
area of distribution ofthe plant in relation to the nesting behavior and
the rhythm of activity of its associated ant species.

P’-9. Dejean A, Corbara B, Orivel J, Snelling RR, Delabie JHC & Belin-Depoux M. 2000. The importance of ant gardens in the pioneer vegetal formations of French Guiana. Sociobiology, 35 : 425-439.

Abstract

We compared the spatio-temporal distribution of arboreal ant species in pioneer vegetal formations of three different ages in French Guiana in order to examine the ants\’ role in the dynamics of this suspended habitat. Among the types of arboreal ant nests, ant gardens were significantly the most frequent, whatever the age of the pioneer formation ; myrmecophytes sheltering ants in domatia occupied the second position. Other kinds of arboreal ant nests (silk or carton nests ; opportunistic nesting in hollowed rotten branches or between tree bark and epiphytes ; nesting in the ground at the bases of trees) were recorded at lower levels. Among the ant species able to build ant gardens, the Ponerinae Pachycondyla goeldii was unexpectedly predominant in young formations. However, its presence decreased as a function of the age of the formation, while ant gardens sheltering Camponotus femoratus or Crematogaster limata parabiotica, either alone or in parabiosis, increased. The epiphytic composition of the ant gardens depended on the ant species sheltered. In parabiosis, this composition was mostly influenced by C.femoratus. This information enabled us to confirm our hypothesis that the nature of the ant species distribution and its accompanying impact on pioneer vegetal formations is not static, but changes over time.

P’-8. Dejean A, Orivel J, Durand JL, Ngnegueu PR, Bourgoin T & Gibernau M. 2000. Interference between ant species distribution in different habitats and the density of a maize pest. Sociobiology, 35 : 175-189.

Abstract

A field study conducted on maize plants growing in three different conditions (one or two rows cultivated along the walls of, houses in working-class districts of Yaounde, Cameroon ; vacant lots of the city that we call urban gardens ; and an experimental field outside the city revealed that the plants were attacked by the corn delphacid, Peregrinus maidis (Ashmed) (Homoptera ; Delphacidae), a vector of maize viral diseases. Damages were significantly greater (1) along the walls than in the urban gardens ; (2) in the urban gardens than at the edges of the field ; and (3) at the edges than in the center of the field. The number of P. maidis individuals per plant was greater on maize plants growing along the walls than in the urban gardens, while we did not record differences between the latter and those situated along the field edges or between edge and center of the fields, We recorded a significant correlation between ants and P. maidis presence an maize plants. Destruction of ant nests by ploughing resulted in less ants foraging on maize and consequently fewer plants attacked by P. maidis. Ant species compete to attend P. maidis, although attendance is influenced by varying ant distribution patterns under the three growing conditions. The number of P. maidis individuals per maize plant varies as a function of the attending ant species. Comparison with controls where ants were excluded indicated no differences in levels of P. maidis when attended by Paratrechina longicornis (Latreille), while other comparisons with the controls resulted in significant differences. The number of P. maidis individuals per maize plant was significantly higher when attended by Camponotus acvapimensis (Mayr) than by Crematogaster sp, or Pheidole megacephala (F.) and was also higher when attended by both of the latter than by Myrmicaria opaciventris (Emery). We therefore advise (1) to avoid growing maize along the walls of houses in the cities, (2) to destroy ant nests situated in and around the urban gardens, and (3) to plough prior to planting maize over a large zone around the fields.

P’-7. Orivel J, Souchal A, Cerdan P & Dejean A. 2000. Prey capture behavior of the arboreal ponerine ant, Pachycondyla goeldii (Hymenoptera : Formicidæ). Sociobiology, 35:131-140.

Abstract

Pachycondyla goeldii, one the rare arboreal ponerine ants, is a generalist predator. We compared its predatory behavior when confronted with different insect prey taxa. The sequence of prey capture is very similar to those of other generalist predators of the subfamily Ponerinae. The agility and swiftness of the workers enabled them to catch most insect prey before they escape by flying away, jumping or falling to the ground. Prey detection was mostly from a short distance and followed by a very rapid attack, generally without any antennal. palpation, resulting in a random seizure. Almost all of the active prey were stung at least one time during capture, even small prey that were easily mastered by the ants. This predatory behavior consisting in shortening the sequence of capture, with stinging almost obligatory, is therefore well adapted to arboreal life as it permits the capture of arboreal insects that have developed different antipredator strategies. Prey retrieval was direct and conducted solitarily, suggesting the existence of orientation cues. P. goeldii foragers palpated anaesthetized prey significantly more often than they did active prey, while it was the contrary for stinging. The reserve behavior displayed when a prey succeeded in escaping is very similar to those already described. These results are compared to those known for other Pachycondyla species and discussed with reference to the adaptation to arboreal life.

P’-6. Orivel J & Dejean A. 1999. L’adaptation à la vie arboricole chez les fourmis. L’Année Biologique, 38 : 131-148.

P’-5. Corbara B, Dejean A & Orivel J. 1999. Les « jardins de fourmis », une association plantes-fourmis originale. L’Année Biologique, 38 : 73-89.

P’-4. Dejean A, Corbara B & Orivel J. 1999. The arboreal ant mosaic in two Atlantic rain forests. Selbyana, 20 : 133-145.

P’-3. Schatz B, Orivel J, Lachaud JP, Beugnon G & Dejean A. 1999. Sitemate recognition : the case of Anochetus traerghordhi (Hymenoptera ; Formicidæ) preying on Nasutitermes. Sociobiology, 34 : 569-580..

Abstract

Workers of the ponerine ant Anochetus traegordhi are specialized in the capture of Nasutitermes sp. termites. Both species were found to live in the same logs fallen on the ground of the African tropical rain forest. A. traegordhi has a very marked preference for workers over termite soldiers, The purpose of the capture of soldiers, rather than true predation, was to allow the ants easier access to termite workers. During the predatory sequence, termite workers were approached from behind, then seized and stung on the gaster, while soldiers were attacked head on and stung on the thorax. When originating from a different nest-site log than their predator ant, termites were detected from a greater distance and even workers were attacked more cautiously. Only 33.3% of these termite workers were retrieved versus 75% of the attacked same-site termite workers. We have demonstrated that hunting workers can recognize the nature of the prey caste (workers versus termite soldiers) and the origin of the termite colony (i.e. sharing or not the log where the ants were nesting), supporting the hypothesis that hunting ants can learn the colony odor of their prey. This, in addition to the nest-site selection of A. traegordhi in logs occupied by Nasutitermes can be considered as a first step in termitolesty.

P’-2. Dejean A, Schatz B, Orivel J, Beugnon G, Lachaud JP & Corbara B.
1999. Feeding preferences in African ponerine ants : a cafeteria experiment. Sociobiology, 34 : 555-568.

Abstract

In order to know the degree of specialization of 17 ponerine ant species belonging to 10 genera, we conducted three series of experiments : a cafeteria experiment using 12 different food items (10 kinds of prey, bread and honey) ; a second series of cafeteria experiments, but with colonies starved during four days to determine if each ant species has alternative food preferences ; and in certain cases complementary experiments. We distinguished polyphagic species that readily accepted both honey and prey. Other tested ant species are specific predators that accepted honey occasionally or not at all. Among them, we noted generalist predators, and semi-specialized species preying mostly on a single taxa, but able to capture other prey without being starved. Among the oligophagous species preying specifically on a particular taxa, starvation plus complementary experiments permitted us to note alternative prey for three species. For the remaining species, the existence of alternative prey was impossible to demonstrate. Finally, we noted that most of the prey accepted by these ants are animals participating in the degradation of leaf litter and rotten wood lying on the ground. Among them, termites were the most frequently chosen, demonstrating the complexity of their role in rain forest ecology.

P’-1. Dejean A, Schatz B, Orivel J & Beugnon G. 1999. Prey capture behavior of Psalidomyrmex procerus (Formicidæ : Ponerinæ), a specialist predator of earthworms. Sociobiology, 34 : 545-554.

Abstract

Foraging workers of Psalidomyrmex procerus, which specialize in earthworm predation, have a hunting behavior well adapted to this kind of prey. For a total of 106 tested earthworms, they captured entire individuals or a piece of prey in 105 cases from the first encounter (99.9%). Small earthworms were detected by contact, long individuals from a distance. The seizure of small prey by their anterior section permitted the ants to capture them whole, after stinging limited prey movements. Long individuals were seized at any point along their bodies and were not always stung. When seized by their anterior part these prey contracted their muscles and/or wiggled, triggering stinging. When seized by the middle or the distal part of their bodies, the prey autotomized. Workers therefore obtained immobile pieces of prey and did not sting, As a result, the antipredator strategy of the earthworms is advantageous for both predator and prey : the ants easily retrieve prey pieces, while autotomy permits the regeneration of the earthworms. These results are discussed with reference to other predatory ants confronted with tubular shaped prey, such as Tenebrio larvae, with large individuals being seized by the anterior part of their bodies and stung at this level, preventing them from struggling.

Book chapters

JPEG

C-1. Roisin Y, Corbara B, Delsinne T, Orivel J & Leponce M. 2011. Termites in Santo : lessons from a Survey in the Penaoru area. Pp. 128-130. In : The natural history of Santo (Bouchet P, Le Guyader H & Pascal O, eds), Publications Scientifiques du Museum, IRD éditions, Pro-Natura International.

JPEG

C-2. Leponce M, Novotny V, Pascal O, Robillard T, Legendre F, Villemant C, Munzinger J, Molino JF, Drew R, Odegaard F, Schmidl J, Tishechkin A, Sam K, Bickel D, Dahl C, Damas K, Fayle TM, Gewa B, Jacquemin J, Keltim M, Klimes P, Koane B, Kua J, Mantilleri A, Mogia M, Molem K, Moses J, Nowatuo H, Orivel J Pintaud JC, Roisin Y, Sam L, Siki B, Soldati L, Soulier-Perkins A, Tulai S, Yombai J, Wardhaugh C, Basset Y. 2016. Land module of Our Planet Reviewed - Papua New Guinea : aims, methods and first taxonomical results. Pp. 11-48. In : Insects of Mount Wilhelm, Papua New Guinea by Robillard T, Legendre F, Villemant C, & LeponceM, eds). Mémoires du Muséum national d’Histoire naturelle.

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