A new survey outlining honeybee colony losses in the U.S. has scientists scratching their heads: For the first time, beekeepers watched more of their colonies disappear during the summer than in winter.
Summer colony losses reached 27.4 percent, exceeding winter losses that came in at 23.7 percent, according to preliminary results from an annual survey of roughly 6,100 beekeepers released Wednesday by the Bee Informed Partnership, a research partner with the U.S. Department of Agriculture. Overall, colony losses during the 12-month period that ended in April reached 42.1 percent — the second-highest annual loss to date.
“We expect the colonies to die during the winter because that’s a stressful season,” Dennis vanEngelsdorp, an entomologist and director of the survey, told The New York Times Wednesday. “What’s totally shocking to me is that the losses in summer, which should be paradise for bees, exceeded the winter losses.”
Beekeepers tapped for the survey manage a total of 400,000 colonies, representing about 14.5 percent of the United States’ honeybee colonies. Colony losses last year weren’t as dramatic as the declines associated with Colony Collapse Disorder (CCD), which was first identified in October 2006.
However, the losses remain troublesome, given the fact that honeybee pollination services are worth $15 billion annually in the United States. To put that in perspective, one in three mouthfuls in our daily diet directly or indirectly benefits from honeybee pollination, according to the USDA.
Where Are They Going?
Entomologists really aren’t sure what causes bees to mysteriously abandon their colonies, but research has focused on four broad categories: pathogens, parasites, management stressors and environmental stressors. The surprising summer losses in 2014-15 could be attributed to overworked bees.
In the 1940s, 5 million managed colonies buzzed in the U.S., but that total sits at roughly 2.7 million today. And although the number of colonies has declined, honeybees’ workload increases every year, and beekeepers are trucking their pollinators over longer distances than ever before. This type of stress amounts to “death by a thousand cuts,” Gordon Wardell, pollination manager overseeing 90,000 colonies, told the Los Angeles Times.
Last year, researchers working to unravel the mystery of CCD published a study blaming a widely used class of pesticides, known as neonicotinoids, for bees’ vanishing act. Researchers exposed 12 of 18 bee colonies to neonicotinoid pesticides, and left another six untreated as a control. By spring, 50 percent of the treated colonies disappeared, while all but one of the control colonies remained stable; bees in the lost control colony showed symptoms of a parasite infection. The European Union banned the use of several neonicotinoid pesticides two years ago, though pesticide manufacturers in the U.S. blame mites for bees’ plight.
Honeybees aren’t in danger of completely vanishing, but if trends continue, they could certainly make grocery shopping a far more expensive chore.