A Varroa mite up close. The mite could be responsible for the deformed wing virus (DWV) afflicting the honey bees Photo: Scott Bauer/USDA

UK scientists are closer to understanding the recent collapse of many honey bee colonies after studying the transmission of a common bee virus.

Deformed wing virus (DWV) is passed between adult bees and to their larvae by the parasitic mite Varroa destructor. However, new research suggests that the virus does not replicate in the mites, and transmission is through other means.

Researchers at the UK's Rothamsted Research and the University of Nottingham used immunhistochemistry to detect viral particles, and found that DWV did not replicate in mite cells, and was only present in the gut.

"The presence of deformed wing virus in large amounts in mite feces suggests it is picked up during feeding on an infected bee," said Professor Teresa Santillian-Galicia of Rothamsted Research. "However, one important question remains – how is the virus transmitted to bees?"

One possibility is that the mouthparts of the mite become contaminated with the virus during feeding, although the researchers consider this unlikely. At present, not enough is known about the anatomy of the mite or its feeding mechanism to suggest another route of transmission.

"It is likely that the amount of virus acquired by the mite plays an important role in the interaction between deformed wing virus and the Varroa mite," said Professor Santillan-Galicia.

"Full understanding of the interaction between deformed wing virus and the Varroa mite will provide basic information for the future development of more sustainable control strategies against the mite and the virus. Our work provides elements of understanding but further research in this area is needed."

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• UK to improve health of honey bees