It's the billion-dollar question: why did colony collapse disorder, a phenomenon characterized by honeybees disappearing for no apparent reason, appear from nowhere in 2006?
Scientists believe that CCD is caused by a combination of air pollution, climate change, pesticides, and maybe even cell phone use. They've also found virulent pathogens in hives--but it's unlikely that these pathogens are working alone, according to a new study from the University of California, San Francisco.
The study, published this week, followed 20 colonies in a commercial beekeeping operation consisting of over 70,000 hives while they were moved across the country, pollinating crops along the way. The researchers came away with a pattern of infections that can be found throughout the seasons--including 27 honeybee viruses (four of which were previously unknown), six species of fungi, six kinds of bacteria, four species of mites, and a phorid (a kind of parasitic fly which previously had not been observed in honeybees outside California).
But none of those things caused the colonies to collapse. This doesn't mean that the viruses aren't killing off honeybees, but it does suggest that CCD is the result of a number of factors working together to create a particularly lethal situation for bees.
"Clearly, there is more than just exposure involved," said Michelle Flenniken, one of the leaders of the study, in a statement. "We noticed that specific viruses dominated in some seasons, but also found that not all of the colonies tested positively for a virus at the same time, even after long-distance transport in close proximity."
In the end, the study doesn't bring us any closer to figuring out the causes of CCD. But it does offer a baseline level of infections that can be found in healthy colonies--and that may help future researchers to figure out whether the pathogens found in collapsing colonies are abnormal.
[Image: Flickr user James Bowe]