Parasite behind European honeybee colony collapse, researchers say

Spanish researchers say they have identified and were able to remove a parasite they believe is behind the collapse of honeybee colonies in Europe, but it remains unclear whether their findings are applicable to the disappearances of colonies in North America.

Mariano Higes of the Regional Apiculture Center in Marchamalo, Spain, and his colleagues looked at two professional apiaries in Spain. They discovered that the infection Nosema ceranae was the only pathogen present in all the honeybee samples analyzed.

Writing in the April issue of the journal Environmental Microbiology Reports, the researchers said the report is the first linking Nosema ceranae infection to Colony Collapse Disorder, which is called Honey Bee Colony Depopulation Syndrome in Europe.

The group also reports that treating the colonies with the fungicide fumagillin halted colony collapse and cleared the infection from existing colonies.

Nosema ceranae and another closely related strain called Nosema apis are single-celled protozoans that affects bees' digestive systems.

Nosema ceranae has been found in Canadian bee colony samples since the 1990s and has been blamed, along with traditional pests like the tracheal mite and varroa mite, for wiping out Canadian colonies in the last few years.

Colony collapse puzzle

But it is not normally associated with Colony Collapse Disorder, which has puzzled scientists and beekeepers alike since it was first discovered in 2004. Its symptoms are the absence of adult bees with no corpses in the hive, and also the presence of both honey and pollen in the hive.

Rob Currie, a honeybee expert and associate professor of entomology at the University of Manitoba in Winnipeg, said the findings from Spain are interesting, but not necessarily applicable here in Canada.

"The Nosema strain they have there on bees is fairly virulent and can cause collapse of colonies but within North America, the strain we have here may be different," he told CBC News.

"It fits within the same species but it doesn't seem to have the same level of virulence," he said. "What they've shown may be true, but I don't think it's a causal factor on a worldwide basis."

As for the use of the fungicide fumagillin, Currie said scientists and beekeepers have been using it successfully in Canada for years.

Finding a cause for collapsing honeybee colonies has been a mission for entomologists and apiarists worldwide since the disorder was first diagnosed in 2004.

Crucial crop pollinators

Honeybees are important not only for producing honey, but also for pollinating food crops.

Around the world, honeybees pollinate apples, cucumbers, alfalfa, blueberries, almonds, squash, watermelons, cantaloupes and a huge variety of other fruits and vegetables — an important contribution to an industry worth tens of billions of dollars.

In Canada, Alberta is particularly reliant on the insects for production of hybrid canola, while provinces like British Columbia and Ontario rely on them for berry pollination.

Last year about 26 per cent of the more than 600,000 colonies across the country were lost over the winter, according to a June 2008 report from the Canadian Honey Council, an industry group representing both commercial and hobby beekeepers. Normal losses during wintering are usually around 15 per cent.

Currie said it's too early to say how Canadian colonies have fared this winter, but he said anecdotal evidence suggests there have been both good news and bad news stories, he said. Results should start to become clearer in May.