'Higher than historical losses': BC bees face increased risk from deadly viruses

‘Higher than historical losses’: BC bees face increased risk from deadly viruses

A virus that attacks the wing shape of bees is spreading rapidly across Canada, causing British Columbia beekeepers to lose entire colonies.

Bee colonies around the world are being decimated by a mite smaller than your pinky fingernail that carries a deadly virus.

Deformed wing virus (DWV), first discovered in 1982 and transmitted by Varroa mites, deforms a bee’s wings so that it cannot leave its colony to feed. The virus can spread rapidly throughout the colonies, often resulting in mass starvation because fewer bees are able to leave and return with food.

A recent study tracking the prevalence of a highly transmissible DWV-B variant, indicates that increased infection worldwide has led to increased rates of colony losses in temperate regions.

This virus has been circulating in Canada since bee deaths nearly tripled in 2007, said Professor Leonard Foster, chief academic researcher for bees at the University of British Columbia’s BeeHIVE research group.

“While DWV-B has been spreading across the country, we have seen higher than historical losses for bees in all provinces, including British Columbia,” Foster said.

While DWV isn’t the only virus that transmits Varroa mites, Foster said the A and B variants of DWV are certainly the most common.

“The two main variants of deformed wing virus are probably the single biggest bee health problem that is also associated with Varroa resurgence,” he said.

The most dangerous type of transmission from mites to bees is when the mites attach to the egg or larva, according to Foster.

“If an adult becomes infected, there is no effect on the bee,” Foster said. “But if an egg or a larva gets infected, the virus causes something to go wrong with the development of the wings.”

Foster explained that symptoms can range from a slightly deformed wing to an vestigial or no functioning wing, to no wing at all.

Beekeepers lose bees and money

The increasing spread of the virus in British Columbia is not only killing bees, but also collapsing the livelihoods of beekeepers. While beekeepers have been able to stay afloat in recent years, Foster said, the ongoing spread of DWV and other viruses is making it increasingly difficult to earn a living.

“As more beekeepers are deciding to go out of business because there are too many of these health threats to bees to be able to maintain a viable business, that means fewer bees,” he said.

Professor Robert Paxton, co-author of the latest study on the prevalence of the DWV-B variant, said in an emailed statement that beekeepers are likely to incur greater losses to the colony this year than in the past.

Paxton writes that beekeepers need to become increasingly vigilant in controlling Varroa mite infestations, especially during the winter months.

Preventive measures

So, how do beekeepers fight to keep DWV out of their colonies? This depends on time, resources and ethics, Foster said.

“There is no equivalent vaccine in bees for viruses,” he said. “The only mechanism that beekeepers have is to control Varroa mites, the vector that transmits the virus between colonies.”

While the most effective preventative measures include constant monitoring and use of chemicals, Foster said some beekeepers would prefer not to use chemicals and would use alternative measures.

These alternative actions could include freezing male bee larvae, which are more appetizing to moths than female larvae, to kill the moths, and dousing the bees in icing sugar, forcing the moths to separate from the bees.

Despite growing concern about DWV and the global spread of its B variant, Foster said it’s important to remember that bee health is more complex than just a single virus.

“This DWV-B is certainly not the only problem that bees face.”

2022-06-07 01:36:47

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