Mite-virus alliance could be bringing down honeybees

A mite and a virus are in cahoots in an attack on honeybee health.

The parasitic mite Varroa destructor feasts on bees of all ages and reproduces on pupae. As the mite travels through bee colonies, it can spread deformed wing virus, which can cause crippled wings and death in extreme cases. By suppressing a bee’s immunity, the virus may improve a mite’s ability to feed and breed on baby bees, researchers in Italy report March 7 in Proceedings of the National Academy of Sciences.   

Mites were more likely to become mothers on Italian honeybee larvae with higher levels of viral infection, the team found. The number of mites that successfully laid eggs soared from 22 percent on bee larvae that developed normally to 40 percent on bees with infections severe enough to cause crippled wings. Still, mite fertility decreased again on bees with very high levels of viral infection. Understanding the complexities of this mite-virus collusion could help explain the factors leading to colony losses and protect honeybees in the future, the researchers say.