The role of the environment on wild bee microbiomes

Wild bees are important pollinators that are facing the effects of changing environments due to anthropogenic activities. Particularly sensitive to changes in environmental surroundings are bee microbiomes, or the microorganisms forming symbiotic relationships with their bee host. This thesis examines the role of environmental factors such as land use, microclimates, and pesticide residues on the microbiota within a small carpenter bee, Ceratina calcarata. Chapter I provides a review of the literature on bee microbiomes and environmental effects on community composition. In Chapter II, urban land use gradients were examined to characterize the microbiome of wild bees in Toronto. In Chapter III, urban and rural landscapes were studied on a broader scale, finding that bees and their pollen provisions from the city harbour different microbes from their agricultural counterparts. This research provides important implications on how anthropogenic activities may be disrupting bee microbiota and causing dysbiosis potentially harmful to pollinator health.