Research conducted in Hawaii by scientists from the University of Hawaii and Britain's Sheffield University showed how Varroa mites caused the so-called Deformed Wing Virus to increase its frequency among honeybee colonies from 10 percent to 100 percent.
Varroa mites live on the surface of honeybees, feeding off their blood and reproducing on their developing brood.
The mites facilitate the spread of viruses by acting as a viral reservoir and incubator, researchers said.
While the virus is naturally transmitted between bees via feeding or during mating, the mites introduce it directly into the bee's blood while feeding, creating a new viral transmission route that bypasses many of the bees' natural defensive barriers, the scientists said.
A million-fold increase in the number of virus particles infecting each honeybee and a massive reduction in viral strain diversity led to the emergence of a single virulent DWV strain now being spread by the mites, they said.
This ability of the mites to permanently alter the honeybee viral landscape may by a key factor in the recent colony collapse disorder seen around the world, a University of Sheffield release reported Thursday.