Diseases spread to wild bees

19 February 2014 by Alex Peel

Diseases that have affected managed honeybee colonies for a number of years have now spread to wild bees, according to new research.

Bumblebee on a flowerThe study, published in Nature, says deformed wing virus and the fungal parasite Nosema ceranae - both of which are thought to have played a key role in honeybee declines - are now widespread in wild bee populations throughout Britain.

Dr Matthias Fürst, from Royal Holloway, University of London, led the study.

"There have been occasional reports of these two diseases being detected in wild bees, but this is the first study to look at the problem on a landscape scale across Great Britain," he says.

"Our results suggest that emerging diseases, spread from managed bees, may be an important cause of wild bee decline."

The team infected bumblebees with deformed wing virus in the lab. This proved that they were more than just carriers of the disease - the disease developed into an active infection that grew within the insect.

Bumblebee on back

Bumblebee on back

They then collected honeybees and bumblebees from 26 sites around Britain. They found that in areas where infection levels were high in managed honeybees, they were also high in wild bumblebees.

Honeybees and bumblebees often forage on the same flowers, and Fürst says this is probably the most common pathway through which the diseases spread from one to the other. But he suspects so-called robbing, where bumblebees try to steal honey from honeybee colonies, may also play a role.

Bees infected with deformed wing virus in their development stage can be left with crippled wings and bloated abdomens, rendering them completely unable to fly. But the effects are often more subtle.

In this study, most bumblebees infected with the virus were still able to fly, but had two thirds the lifespan of healthy bees.

Although managed honeybee colonies are often used by farmers to pollinate their crops, there is growing evidence of the importance of wild bees.

I would favour stopping imports almost completely

- Dr Matthias Fürst, Royal Holloway

In 2011, a study carried out by scientists at the University of Reading estimated that wild bees were now responsible for meeting 60 to 80 per cent of the UK's pollination needs.

"It seems to me a bit short-sighted to put all your money on one horse," says Fürst. "It takes extensive care of honeybees just to keep them going, so it makes sense to have a robust wild bee population there as back-up."

In light of their role in spreading diseases to wild bee populations, Fürst would like to see more substantial controls on honeybee colony imports.

"For years there has been almost no regulation of honeybee trading," he says. "Australia is the only country where they have tight controls, and their bees are doing relatively well."

"I would favour stopping imports almost completely to give us a chance of containing the diseases we have. But if you accept that imports are necessary, then the very least we can do is to introduce a proper screening programme to prevent further diseases from spreading."

"The managed honeybee colonies are the only ones that we can really influence, so we need to make sure that they are as healthy as possible."