In tropical rainforest canopies, competition for patchy resources is an important agent structuring ant communities. Given that many species of arboreal ants depend on hollow twigs and other small cavities for nest sites, arboreal ant nest occupancy is likely determined in part by intra- and interspecific aggressive interactions. Thus, nest site availability may play a large role in structuring arboreal ant species distributions (i.e., via both niche filtering and competition). In the forests of Barro Colorado Island in Panama, the arboreal ant, Azteca trigona, is a common and aggressive species that outcompetes at bait sites and influences presence of dominant invertebrate species. To assess the influence of A. trigona on heterospecific ant species access to nest resources, we surveyed 20 Dipteryx oleifera trees, evaluating species richness and community composition, and set up 20 artificial nests in 10 trees with (Azteca treatment) and 10 trees without (control treatment) A. trigona. We hypothesized that community structure and nest usage is mediated by the presence of the behaviorally and numerically dominant ant, Azteca trigona.
Results/Conclusions
Based on preliminary results, artificial nests in control trees had on average 86% occupancy whereas Azteca trees had on average 62% occupancy. Species richness of nest occupancy was on average 2.5 for control trees and 2.6 for Azteca trees. However, in Azteca trees, A. trigona occupied on average 32% of artificial nests that were colonized. Surveys of trees revealed on average 9.5 species in control and 10.4 species in Azteca trees with a similar community composition between the two treatments. While our results suggest no influence of A. trigona on species richness in tree crowns or artificial nests, they do suggest that when present, A. trigona limit occupancy of artificial nest resources by heterospecific ants. A. trigona build their own carton nests and so are not dependent on opportunistic nest sites, yet when present they inhabit about 1/3 of artificial nest space. Thus, our results suggest that the common and aggressive canopy ant, Azteca trigona, is limiting key resources from other arboreal ant species.