Change in Microbial Communities in Solitary Bee Brood Provisions Over Time

Previous research has shown that microbes are associated with bee pollinators in brood provisions, nest material, larval bee cadavers, and on the tongues of foraging adult bees. Less understood, however, is if the microbial communities associated with solitary bees change over time, or if these communities are consistently present throughout the active season of foraging adult bees. Here, brood provisions (pollen and nectar masses provided as food resources for developing bees) were examined to determine if bacteria and yeast changed over a 5 month nest provisioning period. Individual colonies of yeast and bacteria were cultured and isolated from brood provisions of solitary bees from two locations in Northern California. Microbial isolates were amplified by PCR for DNA sequencing of the 16S rDNA region for yeast (primers NL1 and NL4) and bacteria (primers 27f and 1525r). We plan to use an analysis of variance to compare both the absolute and relative abundance of microbes associated with solitary bees at intervals throughout the season. Microbes as resources, or microbial parasitism of provisions, will ultimately be explored for their impact on bee fitness. Moreover, if the presence of microbes in nectar affects pollinator services to plants, then we might expect impacts of microbes on plant fitness and community structure, as well as on bee fitness. At a time when honeybees are suffering from colony collapse disorder, and when our reliance on native bees may be increasing, this work will shed light on important, but understudied aspects of native bee nutrition, reproduction and behavior.