Tuesday, August 25, 2009
In late 2006, something strange began to happen to America’s honeybees. Colonies that were once thriving suddenly went still, almost overnight. The worker bees that make hives run simply disappeared, their bodies never to be found. Over the past couple of years, nearly one-third of all honeybee colonies have collapsed this way, which led to a straightforward name for the phenomenon: colony collapse disorder (CCD).
This might seem like little more than a tantalizing mystery for entomologists, except for one fact: honeybees provide $15 billion worth of value to U.S. farmers, pollinating crops that range from apples to avocados to almonds. Any number of possible causes for CCD have been put forward, from bee viruses to parasites to environmental triggers like pesticides or even cell-phone transmissions. Despite the Department of Agriculture’s allotment of $20 million a year for the next five years to study CCD, it’s still a mystery – and the bees keep dying. (Read “Why We Should Care About Dying Bees.” )
A new study in the Proceedings of the National Academy of Sciences (PNAS) shows that the causes of CCD may be more varied than scientists expect. The bees may be dying not from a single toxin or disease but rather from an assault directed by a collection of pathogens. A research team led by entomologist May Berenbaum at the University of Illinois compared the whole genome of honeybees that came from hives that had suffered from CCD with hives that were healthy. The sick bees exhibited genetic damage that could account for the die-off, and that damage indicated that they might be afflicted with multiple viruses simultaneously. This could weaken them enough to trigger CCD. “It’s like a perfect storm,” says Berenbaum.