[Pollinator] Dramatic decline found in Western bumblebee populations

[David Inouye]

  Dramatic decline found in Western bumblebee populations

Published: Monday, July 27, 2020

A federal review of existing data unveils an alarming trend for the 
Western bumblebee population, which has seen its numbers dwindle by as 
much as 93% in the last two decades.

The find by the U.S. Geological Survey will help inform a species status 
assessment to begin this fall by the U.S. Fish and Wildlife Service, 
which may ultimately add the insect to its endangered species list.

Tabitha Graves, senior author of the study and a research ecologist with 
the survey, said the trend with the western bumblebee documented between 
1998 and 2018 is troubling because of their important role as pollinators.

"They contribute a lot of money in terms of pollination services for our 
food crops," she said. "Seventy to 80% of flowering plants and crops are 
pollinated by animals overall. Pollination contributes to $20 billion in 
agriculture in the United States."

Bumblebees also pollinate plants in the wild, such as huckleberries, 
which are a staple food source for bears.

There are multiple factors at play that are contributing to the demise 
of the bumblebee, including pesticides, habitat fragmentation, a warming 
climate and pathogens, researchers say.

"People started to notice these declines in the 1990s. This bumblebee 
that was once very widespread and common is something that people 
started to see less frequently," said Diana Cox-Foster, research leader 
and location coordinator at the U.S. Department of Agriculture's 
Pollinating Insects Research Unit at Utah State University.

"There are localized populations where it is still happy and healthy, 
but there have been declines in large parts of its previous 
distributions. ... Asking why these declines are happening is very 
important."

There are concerns that other species of bumblebees used in commercial 
pollination are spreading pathogens to the western bumblebee, Cox-Foster 
added.

"The role of pests and pathogens is of particular concern," she said. 
"There is also climate change and how that has affected the distribution 
of the bee. Agrichemicals are also part of the stress issue."

Graves said the research doesn't point to one conclusive cause for the 
decline, which will be the focus of another research effort to better 
quantify particular threats.

"We have a sample design and have identified where we have gaps in 
knowledge," Graves said. "There are a lot of places in western North 
America where we have not done sampling for bumblebees for a long time. 
We need to support this kind of monitoring and research."

To that end, residents can get in on the action by downloading an app at 
bumblebeewatch.org and documenting what bumblebees they may come across. 
There have been an estimated 14,000 submissions from all 49 states where 
bumblebees occur.

Cox-Foster also added that people can plant bee-friendly vegetation to 
encourage their presence around homes.

"Planting for bumblebees, or all bees, is really important," she said. 
"One of the major issues facing pollinators is lack of floral 
resources." — /Amy Joi O'Donoghue,/ Deseret News/, via Associated Press/


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