The rusty-patched bumblebee gets its name from this rust-colored patch on its back. (Photo: Sam Droge/USGS)
One bumblebee in Virginia is generating a lot of buzz. That's because it's a rusty-patched bumblebee, the first one to be seen in the Eastern U.S. since 2009. Scientists had thought the species was locally extinct and headed for full-blown extinction, but then a research team from the Smithsonian Conservation Biology Institute found one buzzing around Virginia's Sky Meadows State Park.
And where there's a worker bee there must be a colony — at least for now.
Once common across a swath of eastern North America, the rusty-patched bumblebee vanished from 87 percent of its range in recent decades, and its five-year absence led many scientists to conclude we'd seen the last of this species in the Eastern U.S. The cause of its disappearance isn't known, but it might be related to the invasion of Nosema bombi, a parasitic European fungus that's already blamed for the sudden decline of several other U.S. bumblebee species, including the American bumblebee.
"In 20 years of studying bees, I have never seen a rusty-patched," University of Virginia entomologist T'ai Roulston says in a statement about the finding. "Where there is a worker bee, there is a colony and maybe more than one. As they've gone underground for the winter, we can actively look for the colony next spring, and study them and what might be affecting the species."
Along with Smithsonian researchers Bill McShea and Tom Akre, Roulston surveyed bee populations at 17 sites in Virginia this summer, part of an effort to assess the effects of land management on bee diversity. Although they found 35,000 individual bees from 126 different species, they found just the one rusty-patched bumblebee (named after a distinctive reddish spot on the back of its abdomen).
"We thought this bumble bee was extinct in this region," McShea says. "Finding one bee, well this is the stuff conservationists live for. The decline of bee species is of great conservation concern and scientists are actively investigating potential causes to figure out what the culprit is. If we lose bees, we lose critically important pollinators."
The U.S. is home to nearly 50 native bumblebee species, but several are at risk of extinction. (Photo: Bjorn Watland/Flickr)
About a third of humanity's food supply relies on insect pollination, most of which is perfomed by bees. Any while domesticated honeybees' colony collapse disorder gets more attention, many wild bee species — including native bumblebees — are quietly suffering a similar fate.
Several American bumblebee species are in "catastrophic decline," according to the Xerxes Society for Invertebrate Conservation, such as the Franklin's bumblebee, which hasn't been seen since 2006. No single cause has been implicated for such losses, but exposure to common pyrethroid pesticides has been shown to stunt the growth of baby bumblebees, resulting in smaller workers who are less effective foragers. Researchers in the U.K. have also found that honeybee diseases are jumping to wild bumblebees. And according to the Smithsonian, an array of wild bees are at risk due to habitat loss and climate change as well as pesticide use and introduced disease.
While a rusty-patched bumblebee was last spotted in 2009, the species hasn't been seen across most of its range since 2003, despite several surveys aimed at finding it. Now that researchers know there's at least one colony left in Northern Virginia, Roulston is anxious to learn why these rare bees are still there.
"We've either found rusty-patched bumble bees that have developed a resistance," he says, "or we've discovered one of the last colonies and will get one more glimpse before they disappear forever."
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