Washington, June 30 : British researchers have made a significant discovery about the transmission of a common claim that they have made a significant infectious agent called deformed wing virus (DWV), which is believed to be the cause of the recent demise of billions of honeybees.
It is widely believed that this virus replicates in a parasitic mite called Varroa, and gets transmitted to bees when it bites.
However, researchers at Rothamsted Research and the University of Nottingham have discovered that the virus does not replicate in Varroa, suggesting an alternative means of transmission.
"Experiments and field observations have shown that V. destructor is able to transmit several different unrelated honey bee viruses, like acute bee paralysis virus and Kashmir bee virus as well as deformed wing virus. But we still don't know exactly how these viruses are passed from the mite to the bee," said Professor Teresa Santillan-Galicia from Rothamsted Research.
To understand how the virus is transmitted, the researchers decided to study whether the virus replicates in the mites, and if so, where that would occur.
For that purpose, the research team employed a process called immunohistochemistry, which involves the use of antibodies that bind to specific surface proteins and, thereby, help locate the virus particles.
The researchers observed that there was no evidence of virus replication within the cells of the mite.
Professor Santillan-Galicia said that the virus was found only in the lumen of the gut, suggesting that it was merely eaten.
"The presence of deformed wing virus in large amounts in mite faeces suggests it is picked up during feeding on an infected bee.
However, one important question remains - how is the virus transmitted to bees?" said Professor Santillan-Galicia.
The researchers dismissed the possibility that the mouthparts of the mice could become contaminated with the virus during feeding, saying that Varroa mites could nto regurgitate their gut contents because there was a membrane in the oesophagus that acts as a non-return valve.
They said that it was unfortunate that no enough was known about the anatomy of the mite, or about their feeding mechanism, to suggest other routes 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. 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," said Professor Santillan-Galicia.