Bumblebees at risk over spread of deadly virus

ONE of the country’s most important pollinators could be at risk from the same disease that is decimating honeybee colonies across Europe, new research shows.

The Varroa destructor mite lives on honeybees and can spread a dangerous virus throughout the hive.

Now University of Exeter scientists have found that the mite can turn honeybees into “super spreaders”, infecting wild bumblebees.

The Varroa mite has emerged as a parasite of Western honeybees, after switching from its original host, the Asian honeybee, at the beginning of the last century. It has since spread globally through the man-made movement of infested honeybee hives and has turned into a vector of the deformed wing virus (DWV).

The virus is suspected of causing the wing and abdominal deformities often found on adult honeybees in colonies infested with Varroa mites. Symptoms include damaged appendages, stubby, useless wings, shortened, rounded abdomens, miscolouring and paralysis of the legs and wings.

The invasive mite does not live on bumblebees, but the Exeter scientists have discovered it indirectly affects them by raising infection rates among honeybees, which then spread DWV to nearby bumblebees.

The researchers say their findings highlight the need for beekeepers to treat honeybee colonies affected by mites in order to protect wild bees.

“We compared areas where honeybees had Varroa destructor mites with mite-free areas,” said Dr Robyn Manley, of the Centre for Ecology and Conservation on the University of Exeter’s Penryn Campus in Cornwall.

“In areas where mites were present – and therefore spreading DWV among honeybees – we found higher rates of the virus among wild bumblebees.

“Infected honeybees share their environment with bumblebees, feeding on the same flowers and passing on the virus. In effect, the mites turn honeybees into ‘super spreaders’ of DWV.”

A large proportion of honeybees in Britain and many other countries live in hives kept by beekeepers, and Dr Manley said the study raised an important point for them.

“Some beekeepers prefer not to intervene if mites appear in their colonies, but this could be endangering wild bees,” she said.

In effect, the mites turn honeybees into ‘super spreaders’ of

DWV DR ROBYN MANLEY