Azteca ants maintain unique microbiomes across functionally distinct nest chambers

The microbiome of built structures has considerable influence over an inhabitant's well-being, yet the vast majority of research has focused on human-built structures. Ants are well-known architects, capable of constructing elaborate dwellings, the microbiome of which is underexplored. Here, we explore the bacterial and fungal microbiomes in functionally distinct chambers within and outside the nests of Azteca alfari ants in Cecropia peltata trees. We predicted that A. alfari colonies (1) maintain distinct microbiomes within their nests compared to the surrounding environment, (2) maintain distinct microbiomes among nest chambers used for different functions, and (3) limit both ant and plant pathogens inside their nests. In support of these predictions, we found that internal and external nest sampling locations had distinct microbial communities, and A. alfari maintained lower bacterial richness in their ‘nurseries’. While putative animal pathogens were suppressed in chambers that ants actively inhabited, putative plant pathogens were not, which does not support our hypothesis that A. alfari defends its host trees against microbial antagonists. Our results show that ants influence microbial communities inside their nests similar to studies of human homes. Unlike humans, ants limit the bacteria in their nurseries and potentially prevent the build-up of insect-infecting pathogens. These results highlight the importance of documenting how indoor microbiomes differ among species, which might improve our understanding of how to promote indoor health in human dwellings.

SOCIAL WASP FAUNA (HYMENOPERA: POLISTINAE) FROM THE CAATINGA AND THE ATLANTIC FOREST OF THE STATE OF BAHIA, BRAZIL

In this work, we carried out an inventory of social wasps (Hymenoptera, Polistinae) from remnants of Caatinga and Atlantic Forest from the central-south region of the state of Bahia. Nest sampling was carried out in the period from March 2010 to June 2011, using the method of active search. We obtained 90 nests and identified 22 species, three subspecies and one morphospecies of social wasp belonging to ten genera and eight subgenera. Five species were recorded for the first time in the state of Bahia, and the genus Polybia was the most frequent one, with seven identified species. The obtained results confirmed the diversity of the Atlantic Forest, and point to a rich fauna of social wasps in the Caatinga.