UW researchers publish on the decline of the Western bumblebee - Casper, WY Oil City News
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UW researchers publish on the decline of the Western bumblebee

Christy Bell, a Ph.D. student in the UW Department of Zoology and Physiology, observes a Western bumblebee. Bell and Lusha Tronstad, lead invertebrate zoologist with the Wyoming Natural Diversity Database, are co-authors of a paper about Western bumblebees. (Christy Bell)

CASPER, Wyo —  A University of Wyoming (UW) researcher and her Ph.D. student have spent the last three years studying the decline of the Western bumblebee. Their paper, titled “Western Bumble Bee: Declines in the United States and Range-Wide Information Gaps,” was published online June 26 in Ecosphere, according to a UW release Monday. The journal  publishes papers from all subdisciplines of ecological science.

Lusha Tronstad, lead invertebrate zoologist with the Wyoming Natural Diversity Database (WYNDD), and Christy Bell, her Ph.D. student in the Department of Zoology and Physiology, have been working with a group of bumblebee experts to fill in gaps of missing information from previous data collected in the western United States. Their goal is to provide information on the Western bumblebee to the U.S. Fish and Wildlife Service while it considers listing this species under the U.S. Endangered Species Act, the university release said.

Tronstad and Bell are members of the Western Bumble Bee Working Group, a group of experts on the species which came together to pool knowledge on the species, Tronstad said. The paper highlights knowledge gaps, specifically the lack of sampling data in Alaska, northwestern Canada and the southwestern United States.

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“The data we assembled will be used by the U.S. Fish and Wildlife Service to inform its decision on whether or not to protect the Western bumblebee under the U.S. Endangered Species Act,” Tronstad said. “At WYNDD… our mission is to provide the most up-to-date data on which management decisions can be based.”

“The decline of the Western bumblebee is likely not limited to one culprit but, instead, due to several factors that interact such as pesticides, pathogens, climate change and habitat loss,” said Tronstad. “Western bumblebees were once the most abundant bumblebees on the West Coast of the U.S., but they are much less frequently observed there now. Pathogens (or parasites) are thought to be a major reason for their decline.”

Christy Bell (foreground) sets up traps to collect Western bumblebees in southwestern Wyoming. (Lusha Tronstad)

Tronstad said there are several things that homeowners or landowners can do to help this species of bumblebee survive and thrive. These include:

  • Plant flowers that bloom throughout the summer. Make sure these flowers have pollen and produce nectar, and are not strictly ornamental.
  • Provide a water source for bees. Tronstad says she adds a piece of wood to all of her stock tanks so bees can safely get a drink. 
  • Provide nesting and overwintering habitat. Most bumblebees nest in the ground, so leaving patches of bare ground covered with litter or small mammal holes will benefit these bees. Be sure not to work these areas until after you see large bumblebees (queen bees) buzzing around in the spring, usually in April for much of Wyoming, so you can find out where they are nesting.

Tronstad said Bell’s research will continue this summer.

Read the full UW release here.

Other contributors to the paper are from the U.S. Geological Survey; U.S. Fish and Wildlife Service; Canadian Wildlife Service; Xerces Society for Invertebrate Conservation in Portland, Ore.; British Columbia Ministry of Environment and Climate Change Strategy; University of Hawaii-Hilo; U.S. Department of Agriculture; The Institute for Bird Populations; University of Vermont; Utah State University; Ohio State University; Denali National Park and Preserve; and the Royal Saskatchewan Museum.