Rare bumblebee rebounding? Sightings create a hopeful buzz
A group of citizen scientists hopes to document a possible recovery by the Western bumblebee, which almost vanished in many places in the 1990s.
Seattle Times science reporter
See a white-rumped bumblebee?
To report bumblebee sightings, contact the Xerces Society Bumble Bee Watch program: www.bumblebeewatch.org
For Will Peterman, the first thrill was spotting a rare, Western bumblebee north of Seattle last summer.
The second was when the calls and emails started rolling in.
Once abundant throughout the Western United States, the bumblebee with the distinctive white rump began to disappear in the 1990s. By the time Peterman made his discovery, some experts feared it was gone forever from the Puget lowlands.
But after Peterman’s “six-legged Bigfoot” was publicized, scores of people stepped up to say they, too, had seen the species buzzing around their neighborhoods.
Like Bigfoot sightings, the majority of the reports didn’t pan out. But several did.
Peterman and a corps of volunteers have since confirmed colonies near Everett, Lynnwood, Tacoma and on the Olympic Peninsula.
Now, he hopes to conduct a more thorough survey to find out if the species called Bombus occidentalis may be on the rebound and — perhaps — evolving resistance to the disease scientists suspect triggered the population crash.
“At the top of our list is figuring out what’s going on with the recovery — if it really is a recovery,” said Peterman, a writer, photographer and self-described “bee nerd.”
He has assembled an impressive list of collaborators, including scientists at the University of California, Davis, and the U.S. Department of Agriculture (USDA). What he doesn’t have is money.
So Peterman and his volunteers — mostly University of Washington students — have turned to crowdfunding with an Indiegogo campaign to raise $12,000.
That’s enough for three or four people to travel Washington, Oregon, Idaho and several Rocky Mountain states this summer in search of Western bumblebees, Peterman said. In addition to counting insects and noting their locations, the volunteers also plan to collect cell samples for DNA analysis.
The DNA tests, which will be performed at no cost by the USDA’s Bee Biology and Systematics Lab in Utah, may reveal genetic shifts in the species or characteristics that have allowed some remnant populations to survive while others perished.
“It’s kind of like DNA fingerprinting for bees,” said USDA entomologist James Strange.
Native bumblebees haven’t received nearly as much scientific attention as honeybees, a commercially important nonnative that has been decimated by a mysterious ailment called colony collapse disorder.
While some native bumblebee species are in decline, others remain healthy, Strange said. Otherwise, home gardeners wouldn’t be able to grow tomatoes, which are only pollinated naturally by bumblebees.
Since not all bumblebee species were affected when Bombus occidentalis and a close relative declined precipitously, researchers suspected disease rather than pesticides or environmental degradation.
UC Davis entomologist Robbin Thorp, who documented the decline, blames a gut parasite called Nosema bombi. A definitive link has not been proved, but Thorp and other scientists suspect the bug hitchhiked to North America in the 1990s when Western bumblebees commercially bred in Europe were shipped to the U.S., Canada and Mexico.
Tomato, cranberry and blueberry farmers bought colonies and let them loose in fields or greenhouses, Thorp explained.
Strange and his colleagues at the USDA surveyed much of the West beginning in 2006 and found that Bombus occidentalis was largely gone from about 30 percent of its range, particularly west of the Cascade and Sierra Mountains.
East of the mountains and in high-elevation refuges near the Olympic Mountains and Cascade volcanoes, populations survived, though in lower numbers.
But the species hadn’t been documented in the Seattle area in years when Peterman made his find in 2013, in a small park in the town of Brier.
“It’s really exciting to see them back at sea level,” said Rich Hatfield of the Oregon-based Xerces Society for Invertebrate Conservation.
Hatfield isn’t convinced yet that the species is making a comeback. But a new survey would provide a much better picture of where Western bumblebees are thriving, he said. That information could guide efforts to protect the bees’ habitat and shield them from pesticides that can affect all species and which have caused several bumblebee die-offs recently in Oregon, including one last week at an apartment complex in Eugene.
The Xerces Society and USDA have opened their bumblebee databases to Peterman, to help him zero in on areas where he’s most likely to find the insects.
For DNA sampling, Peterman and his crew plan to net bees, immobilize them through brief immersion in a cooler, then snip off a tiny segment of a middle leg. “It doesn’t kill the bee,” he said. “It doesn’t even change their life span.”
Some males, which are born late in the season and don’t contribute to the maintenance of the colonies, will be collected and examined for parasites and pathogens.
The goal is to gather DNA across a wide geographic range and look for changes that might be affecting the bees’ survival. Previous USDA studies found that after the population crashed, Western bumblebees appeared to lose much of their genetic diversity.
“We’d like to know how these populations are related, how much diversity there is within these populations,” Thorp said. “The genetic studies Will is proposing are really fundamental to those kinds of questions.”
Strange, who is still trying to nail down the role of disease in the species’ decline, holds out hope that Western bumblebees may regain their vigor and be raised commercially again someday — and even transplanted back into their native range.
Peterman’s fundraising campaign is all-or-nothing. If he doesn't hit his $12,000 target by Aug. 1, he doesn’t get a cent.
But he and the volunteers are making plans to hit the road before the end of June, so as not to miss the bumblebees’ summer heyday. If the campaign falls short, he said, he’ll pull the plug, nurse his credit-card bills and try to come up with a Plan B.
“I’m optimistic,” Peterman said, “but we’ll see.”
Sandi Doughton: 206-464-2491 or firstname.lastname@example.org