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Significant bee colony losses common across Canada this spring

June 9, 2022  By University of Guelph

Many beekeepers across Canada are reporting colony losses that are “significantly worse” than in previous years and one parasite is getting the blame: the Varroa destructor mite.

The damage that the mites cause will create “a big challenge” over the next few years for beekeepers, says a University of Guelph expert.

Paul Kelly is the research and apiary manager at the university’s Honey Bee Research Centre (HBRC). He has worked with bees for more than three decades and produces videos on beekeeping for HBRC’s YouTube channel.


“Beekeepers of all scale and experience levels are affected. Some have had total colony losses and others have had normal losses,” Kelly said. “It’s too early to say precisely, but I expect the average local losses will top 50 per cent.”

According to the Canadian Honey Council, beekeepers in Alberta and Manitoba have lost an average of 40 to 45 per cent of their honeybees so far this year. In Quebec, losses are about 60 per cent.

In Ontario, where losses are also about 40 to 45 per cent, beekeepers are appealing to the provincial Ministry of Agriculture for help with rebuilding their hives.

At HRBC, the losses are about 25 per cent, Kelly said. Apiary locations where their hives had unusually high bee populations last spring experienced the greatest colony mortality this spring, which fits a predictable pattern of losses caused by varroa mites, he explained.

“It’s significantly worse than other years, and with a cool spring this year, we will lose more colonies.”

Parasitic pests

A honeycomb covered in honeybees is shown

Varroa destructor mites arrived in North America about 30 years ago and have caused major bee deaths for beekeepers ever since, because the Western honeybee has no defence against them.

The mites are parasites that feed on adult bees and pupae, Kelly explained. After latching onto the bee, they suck out its blood and protein reserves, transmit viruses and reduce the insect’s immune responses.

“They are in every one of our hives. It’s just a matter of how many there are and whether they are causing damage or not,” Kelly said, adding that mite reproductive rates depend on spring weather conditions. With last year’s early spring, they were able to reproduce quickly and wipe out colonies over the fall and winter.

“Early bee population buildup in 2021 provided ideal condition for mite population growth” last year, Kelly said.

It could take beekeepers two to three years to recover from the high colony losses this year, making it especially difficult for those who rely on beekeeping for income, Kelly said.

Beekeepers manage colonies to prevent losses to varroa mites but had limited success due to the early buildup last year. The full extent of the colony losses won’t be known until the end of June, when each province’s ministry of agriculture finishes its survey, Kelly explained.

“More research is needed on varroa mites and honeybees to determine solutions that will keep the problem under control,” he said. The HBRC is testing the use of essential oils and organic acids to kill the mites without harming the bees, and is breeding bees for resistance to the mite, he added.

University of Guelph researchers have conducted extensive research on bees and varroa mites. Among other findings, they have found that neonicotinoid pesticides, or neonics, hinder a bee’s ability to fend off varroa mites, and that a gene linked to grooming may be able to protect them.

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