The mite increases the risk of drone virus

A new mite that transmits a dangerous virus among bees also plays an indirect role in the infection of wild bumblebees.

The mite Varroa destructor lives on honeybees and can spread the deformed wing virus (DWV) throughout the hive.

The mite became a parasite of western western bees after leaving its original host, the Asian bee in the early last century. Since then, it has spread worldwide through the artificial movement of infested bee hives and has become a viral vector.

The invasive mite does not live on bumblebees, but scientists at Exeter University have discovered that it is affecting them indirectly by increasing infection rates among honeybees. , who then propagate the DWV virus on nearby bumblebees.

Researchers say their findings highlight the need for beekeepers to treat bee colonies affected by mites to protect wild bees.

"We compared areas where bees had Varroa destructor mites and mite-free areas," said Robyn Manley, of the Center for Ecology and Conservation Penryn campus of the University. Exeter in Cornwall.

"In areas where mites were present – and thus spread yellow fever virus among honey bees – we found higher rates of virus among wild bumblebees." "Contaminated honeybees share their environment with drones, feeding on the same flowers and transmitting the virus, transform bees into "super-spreaders" of DWV ".

Much of the honey bees in Britain and many other countries live in hives guarded by beekeepers, and Dr. Manley said the study had raised an important point for them. "Some beekeepers prefer not to intervene if mites appear in their colonies, but this could endanger wild bees," she said.

As parasites of pupae and adult honeybees, Varroa destructor mites propagate DWV – which is badociated with considerable colony losses due to increased mortality in winter.

"There is a global epidemic of DWV, due in part to the spread of the Varroa destructor mite," said Professor Wilfert of the University of Ulm, Germany.

"We know that the virus is severely affecting bee colonies.There has been little research on the impact on wild bumblebees, but some studies suggest that it can reduce their lifespan. These results underscore the important role of beekeepers, regulators and landscapers in maintaining the health of managed honeybees and wild bee populations. "

There are different strains of DWV, and the Exeter study confirms the opinion that the DWV-B replaces DWV-A as the most common strain. It is known that DWV-B is more harmful to bees, but it is not yet known if and how strains affect wild bumblebees differently.

The paper, published in the newspaper Letters of ecology, entitled: "Community Impacts of a New Vector: Extending DWV-B Emergence from Varroa Infected Honeybees to Wild Bumble Bee."