Varroa mite is the fiend behind the disappearing bee: Guelph professor Ernesto Guzman explains the root of colony collapse disorder

Imagine a world where bees are extinct: a world without bee stings; culturally abandoned apiphobia; and—most importantly—a world entirely void of natural food. That’s the world that Canadian author Douglas Coupland presents readers in his latest take on the future, Generation A: where contact with even a single honeybee (Apis mellifera) warrants abduction by hazmat suited troops and weeks of interrogation and blood sampling. It is undoubtedly a radical interpretation, but for the last three years, honeybees have been dying fast enough to earn the phenomenon the moniker of colony collapse disorder (CCD).

Perhaps well founded, Coupland’s prophecy might never come to fruition (much to the delight of beekeepers around the world). With funding from the Ontario Beekeepers’ Association; the Ontario Ministry of Agriculture, Food and Rural Affairs; the Natural Sciences and Engineering Research Council; and the Inter-American Institute for Co-operation on Agriculture, University of Guelph environmental biology professor Ernesto Guzman believes he’s figured out the problem.

In a study published last month in the biology journal Apidologie, Prof. Guzman noted that Varroa mites (Varroa destructor) were the cause for over eighty-five per cent of honeybee deaths in Ontario. Varroa mites are typically 1-1.8 mm long by 1.5-2 mm wide, eight-legged parasites that thrive on the blood of honeybees. In leeching off of honeybees, Varroa mites are indifferent to viruses their prey might contract—like deformed wing virus—from which victims can lose use of their wings—or even contract paralysis—and are ultimately left with a reduced life span. But the Varroa is also a parasite by the virtue that it has been sucking life and money out of the beekeeping market and food industry, bite after bite.

The Varroa mite has been a problem for roughly twenty years, but Guzman says, “it’s becoming a stronger problem…because mites are developing a resistance to the chemicals that are being used to treat colonies against them.” In Ontario, colonies have been reducing in size by one third for the last three years, and Guzman recognizes that “It’s not economically sustainable to keep on losing [bees at that rate] and […] to purchase bees or to split colonies in half in order to make up for losses.”

“If they have to do that every year, they’ll be out of the business very soon.”

“It’s important to underscore that one third of the food that we eat in western societies is produced thanks to the pollinating services of bees,” Guzman says. He adds that there is no natural alternative to honeybee pollination. “It would have to be manually or mechanically, which would be more costly.”

For Guzman, the Varroa mite is among three main factors contributing to the disappearing bee phenomenon. He also attributes the mortality rates to insufficient winter food supplies within colonies, as well as splitting colonies too late in the season (fall). Guzman notes that while bees live longer throughout the winter months, splitting colonies in the fall is particularly problematic because queen bees stop laying eggs for the winter, “and in order for a colony to make it to the next season, you have to have sufficient bees in the colony.” Guzman says that is when the Varroa mite is particularly problematic, “in the summer months, there are still plenty of bees being produced by the queen […] to replace those bees that die from the infestation of the mite, but if they shorten the lifespan of those bees by half during the winter, […] they will never see the spring, and there are no replacements.”

While the findings in Guzman’s study are concerned with data from Ontario, he maintains that, “I’m sure the Varroa mite is among the three main factors causing the mortality of bees all over the world.”

With the source of CCD in the know, Guzman’s current project is finding an effective treatment, and he’s not focused on finding a miracle pesticide. “I mean, many more synthetic pesticides can be developed to control the mite, but eventually, [the Varroa] might develop a resistance to all of them.”

Guzman has been working on natural compounds that mites will be less likely to develop resistance to and won’t contaminate the honey, listing thymol and oregano oils as products that have been “very effective” at controlling the mites. Guzman also suggests using bio-control agents like fungi that are naturally occurring in the environment, which agree with bees but not with the Varroa. “A third way of approaching this problem […] would be to develop genetically resistant bees—bees that are naturally resistant against the mite.”



Also published at The Ontarion