URI student surveys bumblebees to identify flowers preferred by each species

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Julia Vieira
URI senior Julia Vieira searches for bumblebees during her research to identify the preferred flowers for each bumblebee species in Rhode Island. (Photo courtesy of Julia Vieira)

KINGSTON, R.I. – December 28, 2020 – A survey of bumblebees in the Ocean State by students at the University of Rhode Island found just six species in the summer of 2019 and 2020, down from the 11 species historically recorded in the state. So a URI senior created the state’s first list of wildflowers preferred by each species of bumblebee in an effort to identify the floral resources needed to increase bumblebee diversity in the region.

Working in collaboration with URI Professor Steven Alm, Julia Vieira observed 1,719 bumblebees of six species foraging on 154 different plants at 18 sites around Rhode Island between May and August 2020.

“I wanted to see if there was a correlation between the flowers present and the bees we were seeing,” said Vieira, an environmental science major who grew up in Seekonk, Massachusetts and now lives in East Providence. “The decline of bumblebees is concerning because they are keystone species that pollinate wildflowers and crops.”

Seventy percent of the bumblebees Vieira observed were of one species, the common eastern bumblebee (Bombus impatiens), a widespread species that is abundant throughout the Northeast. She recorded it foraging on 118 different plants, though most were observed on sunflowers, bee balm and sweet pepperbush.

The rarest species, the yellow bumblebee (Bombus fervidus), was observed just 10 times on 7 different plants. Viera also observed 197 brown-belted bumblebees (Bombus griseocollis) on 32 plant species; 133 specimens of the half-black bumblebee (Bombus vegans) on 33 plants; 102 two-spotted bumblebees (Bombus bimaculatus) on 53 plants; and 16 specimens of the confusing bumblebee (Bombus perplexus) on 11 plant species.

Five of the six species of bumblebee were observed foraging on red clover, white clover and butterfly milkweed. Hairy vetch, yellow wild indigo, bee balm, St. John’s wort and button bush were each fed upon by four species of bumblebees. Sunflowers, asters, goldenrod, coneflower and boneset were also found to be common foraging plants for bumblebees.

“Our rarest bumblebee, Bombus fervidus, is a species of concern in the state and could be in serious decline,” Vieira said. “We need to continue surveying and keep track of the population in the state so we don’t lose them completely.”

During four of Vieira’s 10 observations of the species, the bumblebee was seen foraging on bull thistle, an invasive plant.

“We don’t recommend that people plant bull thistle, so we need to continue monitoring to get a better idea of what it’s preferred flowers are,” she said. “Continued monitoring of the floral resources used by all Bombus species will help to identify changes in foraging behavior as a result of impacts from climate change, habitat loss and invasive species.”

Vieira’s research was supported by the URI Coastal Fellows Program, a unique initiative designed to involve undergraduate students in addressing current environmental problems. Now in its 24th year, the program pairs students with a mentor and research staff to help them gain skills relevant to their academic major and future occupations.

“I loved being outside for this project,” Vieira said. “I felt really connected to nature, and I learned so much about how nature works. Now I really understand pollination and how insects and plants evolved together. It shaped my understanding of the natural world.

“I also learned that I really love pollinators, especially bees, and I wasn’t really aware of that before,” she added. “It has definitely shaped my career goals and what I’d like to be doing in the future.”

When she graduates in May, Vieira plans to enroll in graduate school to continue her studies of bees and eventually continue pollinator research while working at a government agency like the Natural Resources Conservation Service.