At-risk and common bumble bees (Bombus spp.) forage differently in protected areas where they co-occur

Bumble bees are important pollinators in wild and managed ecosystems. In recent decades, some species of bumble bees have declined globally, including across North America. Declines have been reported in certain species of bumble bees historically present in southern Ontario, including: Yellow bumble bee (B. fervidus) (Fabricus, 1798), American bumble bee (B. pensylvanicus) (DeGeer, 1773), and Yellow-banded bumble bee (B. terricola) (Kirby, 1837). Various threats contributing to bumble bee population declines include: land-use changes, habitat loss, climate change, pathogen spillover from managed bumble bee colonies, and pesticide use. A general response to the need for action on pollinator preservation in North America has been to encourage planting “bee-friendly” plants. Previous studies show differences in common and at-risk bumble bee foraging; however, similar data are unavailable for Ontario. Our main research questions are: 1. Is there a difference in at-risk and common bumble bee (Bombus spp.) floral use in protected areas in southern Ontario? 2. Do at-risk and common bumble bees exhibit differences in pollen and nectar collection? We hypothesize that common and at-risk species forage differently, predicting that at-risk species forage on a limited selection of host plants. The results of a redundancy analysis show a difference in foraging between common and at-risk bumblebee species. This would have implications for the planting of appropriate forage as a conservation strategy for at-risk bumble bees in Ontario.