Mild winter could increase mountain pine beetles

February 1, 2021

By: The Working Forest Staff

RED DEER ADVOCATE — A mild winter could lead to an increase in mountain pine beetles in the province, says a central Alberta professor.

Nature relies on cold temperatures to serve as a “major mortality factor” for the invasive, tree-killing beetles, said Ken Fry, an instructor at Olds College’s School of Animal Science and Horticulture.

“We do need prolonged really cold temperatures to significantly impact the population,” said Fry.

“The previous two winters we’ve had fairly significant cold snaps: one before Christmas one year and one Christmas the other year. It’s certainly had an impact in the past, no doubt about it.”

Historically, Mother Nature has been able to keep beetle populations in check with winter-time freezes of -36 C for prolonged periods. While there hasn’t been a severe cold snap in central Alberta to that level this year, there is still plenty of time left in the season.

“The mountain pine beetle … can prepare for colder temperatures. As fall progresses, the beetles in their protected habitat underneath the bark, they begin to produce what is essentially anti-freeze inside of them.

“As the season progresses they produce more and more of these protectants, so their most protected state (occurs) in the December to January period, which is why it takes such severe cold weather to have a significant impact.”

In the months following January, the protection in the beetle lessens because it is not as needed. This means a mild cold snap in February or March can be more deadly for the mountain pine beetles, said Fry.

“If we were to get a substantial cold snap, say in late-February or early-March, and it doesn’t have to be -40, it could be in the -20 range, if the beetles don’t have … protection to the extent they would in the middle of winter, then they are more vulnerable.”

The creatures have been found just outside Rocky Mountain House in recent years and have also been discovered in Clearwater County.

The beetles reproduce quickly, he added.

“Cold temperatures can (bring) the population back from an outbreak status where populations are increasing substantially to just maintaining their existing population,” Fry said.

“That’s pretty much what we’ve seen the last couple of years, it’s maintained their existing population or only reduced them to a certain extent.

“If we do get a fully mild winter, we won’t have that significant knockback, which means their population trajectory would be accelerated. It would be increasing a little more quickly than the normal steady state.”

Mary Reid, professor at the University of Calgary’s Department of Biological Sciences, said the impact mountain pine beetles have to an ecosystem varies.

“It’s maybe not as extreme as it might look when there’s a big outbreak,” she said.

“Their effects aren’t necessarily devastating from an environmental standpoint. Of course, they are taking out the same trees forest companies are particularly interested in, so from that perspective, they aren’t very good.”

The beetles found their way into Alberta over the past 15 years, said Reid.

“Their populations really grew in B.C. and then there were some weather conditions that brought a bunch of them over the mountains,” she said.

“They arrived in various parts of Alberta, southern and northern Alberta, but they seem to be particularly successful in northern Alberta.”

It’s possible they could make their way to the Red Deer area eventually, she added.

“Wherever there are pine trees, they can potentially go,” Reid said.

“There has been concern that there’s nothing now to keep them from spreading across Canada. They haven’t really made it to Saskatchewan yet.”

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