Host and biogeographic patterns of native bee microbiomes

Global bee populations have seen a decline in the last few decades, due in part to habitat loss, climate change, and pesticide usage. An inherited toolkit against such threats, the microbiome, has been identified in social bees, aiding in nutrient uptake and defense against pathogens. Non-social bees, which include most bee species, likely acquire their microbiomes from the environment. However, the factors that drive the structure and variation in most solitary bees remain unclear.

This study aims to identify the host-community and biogeographic drivers of variation in solitary bee microbiomes, by surveying across two regions in the Western United States: coastal wetlands and the southwest deserts. From 15 sites, over 300 hand-net-collected bees from 44 species and 6 families were processed for 16S rRNA gene sequencing. We found that solitary bees tended to host relatively simple microbiomes. Habitat type, geography, and bee life history were significant drivers of microbiome structure. These findings can 1) further our understanding of how host communities can shape microbe communities and 2) enhance pollinator management by increasing our understanding of what influences microbial transmission—and potentially beneficial or pathogenic microbes-- in native bees.