Date of Award
Bumble bees (Bombus spp.) are declining globally due to parasites, pesticides, competition, habitat loss, and climate change. Historically, eleven bumble bee species were found in Rhode Island. To assess the status of bumble bee species in the state, I conducted a statewide survey using two sampling methods: vane traps and observations on flowers. Bumble bees were collected using vane traps at farms, golf courses, and in residential areas throughout the state from May through September in 2019-2021. Floral observation surveys were performed in 2020 and 2021 at locations with abundant floral resources to determine the species abundance, diversity, and plant visitation at each site. Floral preferences were also examined based on bee visitation and percent cover of plant species at six transect survey sites in 2021, as well as bumble bee pollen analysis. Our results indicate that only six of the original eleven bumble bee species known from Rhode Island are still found in the state. Bombus impatiens Cresson was the most abundant species in the survey (67.89%), while Bombus auricomus Robertson, a new species record for the state, was the least abundant (0.01%). Bumble bee species richness was highest on Monarda fistulosa L., Trifolium pratense L., and Lavandula angustifolia Mill. Floral transect and pollen analyses also demonstrated the importance of Monarda fistulosa and Trifolium pratense for bumble bee species in Rhode Island. Overall, we did not find B. affinis Cresson, B. citrinus Smith, B. pensylvanicus DeGeer, B. ternarius Say, or B. terricola Kirby, which are likely no longer present in the state. The knowledge gained in this study regarding the floral selection by rare species (B. auricomus and B. fervidus) will be vital to improving bumble bee habitat and species conservation.
Varkonyi, Elizabeth, "BUMBLE BEES (BOMBUS SPP.) OF RHODE ISLAND: RELATIVE ABUNDANCE, DIVERSITY, AND FLORAL VISITATION" (2022). Open Access Master's Theses. Paper 2266.
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