Wildlife

The buzz on bee declines this past winter

  • May 27, 2014
  • 587 words
  • 3 minutes
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With every third bite of food you eat, you should be thanking a honey bee.

They are Canada’s most important pollinators and after a record-setting cold winter, more than 30 per cent of them may have died.

But not all the blame can be put on the harsh temperatures and prolonged frost of the East Coast. New research suggests that neonicotinoids, a type of insecticide, is one of the main causes in the honeybees’ inability to regroup this spring.

“When winter was the only stress, we lost between five to 10 per cent of bees,” says Dan Davidson, President of the Ontario Beekeepers’ Association. “They’ve been dealing with cold for millions of years.”

But when new stressors were introduced, the decline became worse.

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Beekeeper inspecting langstroth bee hives in Alberta. (Photo: Migco)

In the early 1990s, hives started becoming infested with a parasite called Varroa mites, which brought Ontario’s average honeybee winter loss to 17 per cent. But in 2007, neonicotinoids started to be used at a greater rate, and the average winter loss climbed to 35 per cent.

The use of neonicotinoids has been linked as a direct cause of Colony Collapse Disorder, a phenomenon where honeybee colonies abruptly disappear from their hives. But this has been highly debated over the past couple of years. Europe banned the use of neonicotinoids last year, while Canadian and United States authorities have taken a more cautious approach, suggesting these pesticides are just one possible factor in the disorder.

A new report released by Harvard University this year compared honeybee colonies that were exposed to neonicotinoids to ones that were insecticide-free, finding that the real effects were only shown during the winter. Both groups had normal, steady decreases in populations starting in October. But by January, the non-exposed colonies quickly repopulated their cluster size, while the exposed colonies continued to decline. In early April, the majority of honeybees in the exposed colonies had completely abandoned their hives.

Researchers have not yet figured out exactly how these chemicals cause bees to vanish or lose their ability to repopulate when the cold season is over.

“Beekeepers are worried about the systemic nature of these insecticides,” Davidson says. “They’re exposed in all parts of the plant, including nectar and pollen, and it’s hard for a bee to overwinter on poisonous food.”

Unlike other bee species, which overwinter in leaf litter or burrow in the soil, honeybees remain in their hives all winter long. With this past winter being longer than usual, many honeybees ended up starving when they came out from hibernation and found no flowers to feed on.

Davidson says that to make up for winter losses, beekeepers can either make bees from their own bees by providing hives and purchasing new queens, buy bees from a neighbouring beekeeper or import packaged bees from Australia and New Zealand, where the growing season in the Southern Hemisphere is already underway.

Ontario is also offering one-time financial assistance of $105 per hive to beekeepers who have 10 hives or more and lost over 40 per cent of their colonies between January and November of this year.

While many beekeepers are struggling to keep afloat, urbanites with an interest in backyard beekeeping managed to fare a bit better this winter.

“The main reason is that they’re not running up against large monoculture crops where a lot of pesticides are sprayed,” says Tom Nolan of the Urban Toronto Beekeepers’ Association. “That’s one less factor urban beekeepers are dealing with.”

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