Bee Die-Offs Tied to Tobacco Plant 'STD'

Honeybees have been dying in huge numbers since 2006, and a new study finds that a virus may be one cause. The tobacco ringspot virus has mutated quickly and jumped from tobacco plants to soy plants to bees, researchers say, and the annual increase in honeybee deaths between autumn and winter correlates with an increasing number of infections. The virus exists in pollen, and is likely spread as bees mix saliva, nectar, and pollen to feed their larvae; mites may also be transmitting the virus when they feed on bees. (Grist calls the virus a "plant STD," since it's spread as bees pollinate plants.)

It's just the latest explanation offered for "colony collapse disorder," which has decimated about one-third of commercial honeybee colonies per year since 2006, the New York Times reports. The study authors and other researchers believe that a number of factors are to blame, including viruses, parasites, and perhaps pesticides. This is the first known example of bees contracting a virus from pollen. And since 5% of known plant viruses can be transmitted from plant to plant via pollen, researchers think pollen should be monitored for other potential host-jumping viruses, Science Codex reports. (More bee news: It turns out they almost disappeared with the dinosaurs.)