22 Jan 2014:
New Virus Associated With
Massive Bee Die-Offs, Researchers Report
A rapidly mutating virus may be partially responsible for the massive bee die-offs known as colony collapse disorder (CCD), which has wiped out a third of commercial bee colonies annually for the past seven years, a group of U.S. and Chinese researchers reports
. Most scientists, including the study's authors, believe CCD is triggered when colonies are weakened by a combination of factors
, such as viruses, parasites, and perhaps pesticides. The study published yesterday
in the journal mBio
found in bees a variant of the tobacco ringspot virus, an RNA virus that likely jumped from tobacco plants, to soy plants, to bees. Weak bee colonies began succumbing to massive die-offs in autumn, and the researchers found those bees were heavily infected with tobacco ringspot — which is believed to affect honeybees' nervous systems — and other viruses. Strong colonies that made it through the winter showed no evidence of infection by tobacco ringspot or Israeli acute paralysis virus, a second virus commonly implicated in CCD. The researchers believe the virus jumped from plants to bees through "bee bread," a concoction of pollen, nectar, and saliva they feed their larvae. Bee infection by tobacco ringspot is the first known instance of a virus from pollen jumping to bees, but roughly one in 20 plant viruses is found in pollen, the researchers note, suggesting pollen should be monitored as a source of infections.