Asian giant hornets, also known as ‘murder hornets,’ may be all the buzz, but experts and beekeepers say another pest causes beehives more grief.
80 per cent of all honey bee colony fatalities during winter in Ontario can be linked to varroa mites, according to Ernesto Guzman, professor and director of the University of Guelph Honey Bee Research Centre.
Varroa mites, parasites of the honey bee, have been present in Canada since the early 1990s, Guzman said.
The mites feed upon hemolymph — the equivalent to blood — and fat tissue, like “a tick of the honey bee,” Guzman said.
“These parasites not only feed upon these two important tissues of the honey bee, which weakens the insect, but also transmits viruses to the bee,” Guzman explained.
“A single mite can reduce a lifespan of a honey bee by 50 per cent, and therefore it’s considered the health issue number one for the Western honey bee worldwide,” he added.
The mites, along with other factors such as pesticides, have caused honey bee populations to dwindle. 30 per cent of honey bee colonies are lost every year, mostly due to the varroa mites, according to Guzman.
“One third of the food that we consume is thanks to the pollinating services of bees,” Guzman said of the impact the decreasing honey bee population has on humans.
Christa Roettele, a spokesperson for the Ministry of Agriculture, stated in an email that the mite is most likely present in almost all honey bee colonies in Ontario.
Since September 2019, Roettele said the “federal and provincial governments have committed more than $362,000 to support approximately 225 projects through the Canadian Agricultural Partnership targeted intake to support honey bee health management.”
‘Murder hornets’ have garnered much media attention over the month of May, after sightings of the insects in British Columbia.
Despite “exaggerated” concerns over the Asian giant hornet in Canada, Guzman said the hornets’ threat is actually smaller than that of varroa mites because their capacity to spread is limited.
“There are much more difficult problems to deal with, including the varroa mites,” he said.
Beekeeper Brent Halsall of Halsall’s Honey said varroa mites have been his number one problem over his 15 years of beekeeping.
“It’s a battle against them every year,” he said.
Halsall said he lost nearly 90 per cent of his colonies in his early years of beekeeping from mites. He has tried using hard chemical treatments, but now uses organic acids.
“It works well but it’s very labour-intensive, time-intensive,” he added.
Mike Parker of Charlie-Bee Honey in Beamsville, Ont. has also had difficulties with varroa mites in over three decades of full-time beekeeping.
“We’ve used products ever since the mites came in,” Parker said. “The mites become resistant after a period of time, so then we have to switch to another product.”
“Monitoring your mite levels is the most important part and keeping the levels below the threshold is really the key to having healthy bees,” Parker added.
Guzman said monitoring mite levels is a complex issue because an effective method needs to work independent of weather conditions for long periods of time. He’s tested a variety of methods for combatting mites, from the essential oils of oregano and thyme to biopesticides.
“There are many avenues that have been tested and have shown promise in the control of the mites, but the solutions have to be not only effective, but cost-effective and also practical,” Guzman added.
Dan Borges, a research technician for the Ontario Beekeepers’ Association, said he is involved in two breeding projects testing honey bees with traits that control the spread of mites in hives.
At the University of Guelph, Borges and his Ontario Beekeepers’ Association team are working on a breeding project on bees with high levels of grooming behaviour who will aggressively knock the mites off their bodies to prevent infestation.
At Laval University, the association is working on a trait called varroa-sensitive hygiene, Borges said, which tests how bees can control mites early on when they’re reproducing.
Since the invasive mite has only been in Canada for 30 years, there hasn’t been enough time for bee populations to develop a lot of genetic resistance.
“There is some genetic resistance, and bee breeders are trying to make bees that are stronger and healthier and better able to handle it,” Borges said.
Guzman said that if consumers wish to help, they should buy local.
“If you buy locally produced honey, you’re helping your local beekeeper who will have the funds to keep bees alive.”
