Factors influencing bee communities and pollination services across an urban environment

Current declines in the abundance and diversity of bees and other pollinators has created uncertainty in their ability to reliably deliver pollination services. Recent studies examining urban bee communities show that bees respond to urbanization-mediated changes in land-use and environmental conditions. This includes increases in thermal and desiccation threats via urban heat island (UHI) effects that have not been well explored in bees. But it is unclear whether or how urbanization-related changes to pollinators influence pollination services. In this dissertation, I surveyed urban gardens and city parks across the metropolitan region of Toledo, Ohio (USA). First, I examined thermal and desiccation tolerances and safety margins for three bee species: silky striped sweat bees (Agapostemon sericeus), western honey bees (Apis mellifera), and common eastern bumble bees (Bombus impatiens). Second, I examined how urbanization and local habitat characteristics (herbaceous cover, floral abundance and color, tree abundance, canopy cover, soil moisture, gardens size) influenced bee communities (abundance, diversity, composition) and pollination services (visitation frequency). Third, I examined how bee species with specific functional traits and combinations of traits (functional guilds) were influenced by urbanization. The findings from this dissertation suggest that bees have differential sensitivities to urbanization, and managing for diverse bee communities in urban environments may require mitigating changes in temperature and water and increasing floral resource availability