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 wiping out bees across the United States, UC San Francisco researchers said Wednesday.
Researchers have been struggling for months to explain the disorder, and the new findings provide 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 Merced County, UCSF biochemist Joe DeRisi said. "We don't want to give anybody the impression that this thing has been solved."
Other researchers said Wednesday that they too had found the fungus, a single-celled parasite called \o7Nosema ceranae\f7, in affected hives from around the country -- as well as in some hives where bees had survived. Those researchers have also found two other fungi and half a dozen viruses in the dead bees.
\o7N. ceranae \f7is "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 to discuss Colony Collapse Disorder.
"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. Weather, pesticide exposures and infestations by pests, such as the Varroa mite, have wiped out significant numbers of colonies in the past, particularly in the 1960s and 1970s.
But the current loss appears unprecedented. Beekeepers in 28 states, Canada and Britain have reported large losses. About a quarter of the estimated 2.4 million commercial colonies across the United States have been lost since fall, said Jerry Hayes of the Florida Department of Agriculture and Consumer Services in Gainesville.
"These are remarkable and dramatic losses," said Hayes, who is also president of the Apiary Inspectors of America.
Besides producing honey, commercial beehives are used to pollinate a third of the country's agricultural crops, including apples, peaches, pears, nectarines, cherries, strawberries and pumpkins. Ninety percent of California's almond crop is dependent on bees, and a loss of commercial hives could be devastating.
