Study: Western bumblebees decreasing

Neonicotinoid pesticides, climate change among reasons for 57% decline

Western bumblebees are becoming less common in Colorado, dropping nearly 60% since 1998 due to impacts from climate change and the use of a certain pesticide, according to a study by the Proceedings of the National Academy of Sciences.

The U.S. Fish and Wildlife Service was petitioned to list western bumblebees as a threatened or endangered species in 2015, and the academy has been studying specifically western bumblebees since.

“Across the Western U. S., we saw a 57% decrease in the species occurrence,” PNAS biologist William M. Janousek said.

The main focus of the study was to examine the changes in how common the western bumblebee is in the region.

“In 1998, if you were to go to 10 random locations in the (Colorado), you would expect to see them in about seven to eight of those places,” Janousek said. “In 2020, we found that if you were to go to 10 random locations, you might only find the species in about one to three of those 10 locations.”

PNAS biologists point to many reasons behind the decline in the study, but climate change is the main one.

In their testing, they measured the heavy effects of drought and temperature change. The study indicates that the most optimistic scenario for 2050 is that the occupancy of different ecoregions will go down to about half of what they host now.

“…more severe scenarios predict declines in all ecoregions ranging from 51 to 97%,” the authors of the study wrote.

They also found that neonicotinoids are the type of pesticides most heavily affecting the western bumblebee.

Neonicotinoids are a form of pesticide that closely resembles nicotine.

It gets soaked into the soil of plants and disrupts the nervous system of insects.

A major increase in the use of neonicotinoids began in 2004, and since then, there have been multiple studies done on the effect they have on insects.

“Our findings join a substantial body of research implicating neonicotinoids ( particularly the nitroguanidine group) in ongoing wild bee declines,” the study states.

The Colorado Office of Policy, Research, and Regulatory Reform is performing a sunset review of the Pesticides Applicator Act, which regulates who can use neonicotinoid pesticides. Coloradans are allowed to comment on the review, which could result in the repeal of the law.

However, Environment Colorado, a policy action group focused on conservation, sustainability and recycling, wants more action than is currently allowed under the Pesticides Applicator Act going forward.

“The work that we’re doing to save the bees and the actions that we’re calling for in the legislature matter and … they really do have this broad impact and that the bees need help more than ever,” said Natalie Woodland, the Saves the Bees associate at Environment Colorado.

“We are open to different policy mechanisms to get this done, but what’s important is that we take action ASAP to save the bees from bee-killing neonic pesticides,” Woodland said.

Maine addressed this issue in 2018, prohibiting the unlicensed use of neonicotinoids. New Jersey and New York have also passed laws to restrict the use of neonicotinoids.

“We need to take action for pollinators this year. We can’t just keep putting it off. Now is the time to do something about it.” Woodland said.