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.

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.

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.

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.

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.

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. mertensiiC. 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.

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.

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.

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.

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.

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.

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.

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.