PhD Candidate University of California Davis, California
Host-microbe interactions underlie the development and fitness of many macroorganisms, including bees. Whereas many social bees benefit from vertically transmitted gut bacteria, current data suggests that solitary bees, which comprise the vast majority of species diversity within bees, lack a highly specialized gut microbiome. We examined the composition and abundance of bacteria and fungi throughout the complete life cycle of the ground-nesting solitary bee Anthophora bomboides standfordiana. In contrast to expectations, immature bee stages maintain a distinct core microbiome consisting of Actinobacterial genera (Streptomyces, Nocardiodes) and the fungus Moniliella spathulata. Dormant (diapausing) larval bees hosted the most abundant and distinctive symbiotic bacteria and fungi. Streptomyces from brood cells inhibited the growth of multiple pathogenic filamentous fungi, suggesting a role in pathogen protection during overwintering, when bees face high pathogen pressure. We find that Anthophora bomboides hosts a conserved core microbiome that may provide key fitness advantages through larval development and diapause, and explore the potential vertical transmission of the fungal symbiont.
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