Microbial symbiosis in solitary bees: Variation in structure and assembly

For solitary bees, microbial community assembly and composition varies both within and among species. The microbiome of developing and adult bees is hypothesized to affect bee development and survival yet bee species vary in the consistency and diversity of interactions with bacteria and fungi. Here, we present data from bee genera including Osmia, Xylocopa, Anthophora and Diadasia that associate with microbial communities in stored food, developing larvae and adults. These bee species differ widely in the type of host-microbe associations, ranging from variable and diverse microbiomes to consistent, abundant and low diversity communities. We discuss variation in life history among bees and hypothesize potential drivers of variation in host-microbe associations, as well as future research priorities within solitary bee-microbe interactions.