Mite-y bees: bumble bees (Bombus spp., Hymenoptera: Apidae) host a relatively homogeneous mite (Acari) community, shaped by bee species identity but not by geographic proximity: Mite communities associated with bumble bees

1. Parasites can affect the communities of their hosts; and hosts, in turn, shape communities of parasites and other symbionts. This makes host-symbiont relationships a key but often overlooked aspect of community ecology. 2. Mites associated with bees have a range of lifestyles; however, little is known about mites associated with wild bees or about factors influencing the make-up of bee-associated mite communities. This study investigated how mite communities associated with bumble bees (Bombus spp.) are shaped by the Bombus community and geographic proximity. 3. Bees were collected from 15 sites in Ontario, Canada, and examined for mites. Mite abundance and species richness increased with local bee abundance. Several bee species also differed in mite abundance, species richness, prevalence, and diversity. Locally uncommon species tended to have more mites than other bees. Queen bees had the most mites, and males had more mites than workers. 4. Spatial proximity was not a predictor of mite community composition, despite a strong effect of proximity on bee community similarity. 5. On the 11 Bombus spp. examined, 33 mite species were found. Whereas nearly half of these mite species are obligate associates of bumble bees, none was restricted to particular Bombus species. 6. The best predictor of mite community composition was bee identity. Although many parasite communities show strong geographic patterns, the communities of primarily commensalistic bee-mites in this study did not. These findings have implications for bumble bee conservation, given that pollen-feeding commensals might become harmful at high densities or act as disease vectors.