Gut microbes contribute to variation in foraging intensity in the honey bee,Apis mellifera.

Abstract Gut microbiomes are increasingly recognized for mediating diverse biological aspects of their hosts, including complex behavioral phenotypes. Many studies have reported that experimental disruptions to the gut microbiome result in atypical host behavior. However, studies that address the role that natural variation in gut microbial communities plays in naturally occurring host behavioral variation are sparse. Here, we show that variation in the gut microbiome influences variation in foraging intensity in honey bees. Gut microbial community structure consistently differed between hive-based nurse bees and bees that leave the hive to forage for floral resources. These differences were associated with variation in the abundance of individual microbes, including Lactobacillus mellis, Lactobacillus melliventris, and Bifidobacterium asteroides . Manipulations of colony demography and individual foraging experience suggested that differences in microbiome composition were associated with task experience. Moreover, single microbe inoculations with L. mellis, L. melliventris , or B. asteroides caused changes in foraging intensity. These results demonstrate that gut microbiomes contribute to naturally occurring host behavioral variation, and support a model in which positive feedback interactions cause adaptive changes in both gut microbiome composition and host behavior.