A fungus that caused widespread loss of bee colonies in Europe and Asia may be playing a crucial role in the mysterious phenomenon known as Colony Collapse Disorder that is now wiping out bees across the U.S., University of California, San Francisco researchers said Wednesday.
Researchers have been struggling for months without success to explain the disorder, and the new findings represent the first solid evidence pointing to a potential cause.
But the results are “highly preliminary” and are from only a few hives from Le Grand in California’s Merced County, UCSF biochemist Joe DeRisi said. “We don’t want to give anybody the impression that this thing has been solved.”
Others said Wednesday that they too had found the fungus, a single-celled parasite called Nosema ceranae, in hives from around the country. They also have found two other fungi and six viruses in dead bees.
“N. ceranae” is “one of many pathogens” in the bees, said entomologist Diana Cox-Foster of Pennsylvania State University. “By itself, it is probably not the culprit ... but it may be one of the key players.”
Cox-Foster was one of the organizers of a meeting in Washington, D.C., on Monday and Tuesday where about 60 bee researchers gathered.
“We still haven’t ruled out other factors, such as pesticides or inadequate food resources following a drought,” she said. “There are lots of stresses that these bees are experiencing,” and it may be a combination of factors that is responsible.
Historically, bee losses are not unusual. But the current loss is unprecedented. About a quarter of the estimated 2.4 million U.S. colonies have been lost since last fall, said Jerry Hayes of the Florida Department of Agriculture and Consumer Services.
Besides a loss in honey production, commercial beehives are used to pollinate one-third of the country’s crops.
“For the most part, they just disappeared,” said Florida beekeeper Dave Hackenberg, who was among the first to note the losses. “The boxes were full of honey. That was the mysterious thing. Usually other bees will rob those hives out. But nothing had happened.”
Researchers now believe that the foraging bees are too weak to return to their hives.
If Nosema does play a role in Colony Collapse Disorder, there may be some hope.
A closely related parasite can be controlled by the antibiotic fumagillin, and there is some evidence that it will work on N. ceranae as well.