Abstract: Epiphytes represent up to 50% of all plant species in rainforests, where they host a substantial amount of invertebrate biomass. Efficient surrogates for epiphyte invertebrate communities could reduce the cost of biomonitoring surveys while preventing destructive sampling of the plants. Here, we focus on the invertebrate communities associated to tank bromeliads. We ask whether the presence of particular ant and/or spider taxa (easily surveyed taxa) that use these plants as nesting and/or foraging habitats predicts functional trait combinations of aquatic invertebrate communities hosted by the plants. Functional community composition of invertebrates was predicted both by bromeliad habitat features and the presence of certain ant and spider species. The ant Azteca serica preferred wider bromeliad rosettes that trap large amount of detritus, indicating interstitial-like food webs dominated by deposit feeders that burrow in fine particulate organic matter. Leucauge sp. spiders preferred narrower bromeliad rosettes bearing smaller detrital loads, thereby indicating a dominance of pelagic filter-feeding and predatory invertebrates in the water-filled leaf axils. Both Neoponera villosa ants and Eriophora sp. spiders preferred rosettes at intermediate size bearing moderate amounts of detritus, indicating a benthic food web dominated by leaf shredders and gathering collectors. Owing to the animal diversity and biomass supported by rainforest epiphytes, our approach would deserve to be further tested on a range of epiphytes involved in tight interactions with invertebrates. In this context, surrogate species could serve both as indicators of functional diversity, and as early-warning indicators of network disassembly.

Abstract: In French Guiana, the arboreal nests of the swarm-founding social wasp Protopolybia emortualis (Polistinae) are generally found near those of the arboreal dolichoderine ant Dolichoderus bidens. These wasp nests are typically protected by an envelope, which in turn is covered by an additional carton ‘shelter’ with structure resembling the D. bidens nests. A few wasps constantly guard their nest to keep D. bidens workers from approaching. When alarmed by a strong disturbance, the ants invade the host tree foliage whereas the wasps retreat into their nest. Notably, there is no chemical convergence in the cuticular profiles of the wasps and ants sharing a tree. The aggressiveness of D. bidens likely protects the wasps from army ant raids, but the ants do not benefit from the presence of the wasps; therefore, this relationship corresponds to a kind of commensalism. Résumé En Guyane française, les nids de la guêpe Protopolybia emortualis (Polistinae) se trouvent généralement à proximité de ceux de la fourmi arboricole Dolichoderus bidens (Dolichoderinae). Ces nids de guêpes sont typiquement protégés par une enveloppe de carton, elle-même recouverte d’une autre enveloppe formant un abri qui ressemble aux nids de carton de D. bidens. Quelques guêpes gardent leur nid en permanence afin de tenir à distance les ouvrières D. bidens. Alarmées par une forte perturbation, les fourmis envahissent tout le feuillage de leur arbre support alors que les guêpes se réfugient dans leur nid. Il n’y a pas de convergence chimique entre les profils cuticulaires des guêpes et ceux des fourmis associées. Il est très probable que les P. emortualis bénéficient d’une protection contre les fourmis légionnaires grâce à l’agressivité des D. bidens, mais il n’y a pas réciprocité, de sorte que cette relation correspond à une forme de commensalisme.