USDA scientists say they may have found cause of bee colony-collapse disorder

Scientists from the U.S. Department of Agriculture say they may have found the cause for the mysterious Colony Collapse Disorder (CCD) affecting bee populations across the country. In the study, presented at the meeting of the American Society for Microbiology, researchers point to the presence of a fungus and family of viruses as a possible cause, Katia Moskvitch of the BBC reports. Jay Evans, one of the study's researchers with the USDA Agricultural Research Service, said when these two very different pathogens show up together, "there is a significant correlation with colony decline."

Some beekeepers affected by CCD "have been reporting average losses of 30-35% of hives," Moskvitch writes. After collecting samples from sick bees in Florida and California, where most of the U.S. commercial pollination takes place, researchers discovered a higher presence of the fungus Nosema cerenae in infected colonies. "But it was only recently that they were able to determine that it's when bees are infected both with Nosema and with a group of RNA viruses that it is likely to lead to a collapse of a colony," Moskvitch writes.

Still some aren't completely buying the fungus and virus as the cause. "David Mendes, the president of the American Beekeeping Federation, says that biological pathogens are certainly involved - but that there might be something that affects the bees' immune system in the first place that then allows these pathogens to infect them more easily," Moskvitch writes. "It's a bit of a chicken-and-egg question: are the fungi and viruses a problem or are they a symptom?" Mendes said. "Do they come in only when the health of the bees is in some jeopardy? I think the bees get sick because of a combination of factors." (Read more)