Environmental determinants of social wasp diversity and assemblage structure in an Amazonian archipelagic landscape

Hydropower development has become an important driver of habitat loss and fragmentation across lowland tropical forests. Despite ample evidence on the detrimental effects of insular habitat fragmentation on biodiversity, invertebrate taxa, that may be critical to ecosystem functioning, have been overlooked. We assessed the assemblage-level responses of social wasps to forest insularization induced by the Balbina Hydroelectric Dam in Central Brazilian Amazonia. Employing Malaise trapping, we captured wasps on 27 forest islands and three continuous forests. We constructed Generalized Linear Models and employed a model selection approach to examine the impact of local variables (fire severity (FIRE) and basal area of pioneer tree species (PIONEER)) and landscape-scale variables (amount of habitat (COVER)) on patterns of species richness, composition, and body size of wasps. A total of 374 individuals (29 species) were collected across all sampling sites. COVER was the main predictor of species richness, while PIONEER was the only variable that explained variation in community composition, with a negative effect on body size. Our results add evidence to the pervasive impacts of large hydroelectric dams on tropical forest biodiversity, and suggest that social wasps, among other invertebrates, can be used as bioindicators in infrastructure development projects.