Microbial Communities Across Social Roles in Small Carpenter Bee Nests

Bee microbiota form important symbiotic relationships with their hosts, but microbial communities vary across bee species, sociality, and environment. Comparing the microbiome of bees with different social roles and foraging behaviours may uncover the ways in which microbiota are environmentally acquired and subsequently introduced and spread into the nest environment. Here, we performed metabarcoding of the 16S rRNA, ITS, and ribulose biphosphate carboxylase large (rbcL) regions on mothers, dwarf eldest daughters, and regular daughters in nests of the facultatively social, small carpenter bee, Ceratina calcarata, contrasting bacteria, fungi, and plant associates. We also performed two different sampling types by characterizing the microbiome using whole-guts and whole-bodies. Social role in nest impacted the microbial community composition and mothers were found to demonstrate increased plant diversity compared to their daughters, more specifically in whole-bodies, highlighting the ability to determine plants that bees are visiting during foraging through DNA metabarcoding. We also found that metabarcoding of the whole-body recovered increased fungal and plant diversity compared to whole-guts, suggesting that including microbiota from beyond the gut offers an opportunity to characterize uncommon associates that bees encounter, particularly through plant-pollinator relationships. As the transmission of beneficial symbionts and pathogens between individuals are studied for its impact on bee health, microbial analyses of bees across different environments and levels of sociality provides unique biomonitoring that can indicate the health of the larger bee community.