Alberta's mountain pine beetles likely survived recent extreme cold snap, experts say
Beetles produce a type of antifreeze that allows them to survive extreme cold
The recent extreme cold snap likely did nothing to diminish Alberta's destructive mountain pine beetle populations, experts say.
An extreme cold warning issued on Boxing Day brought most of the province to a standstill for almost a week as temperatures dipped into the -40 C range with the wind chill. Extended periods of temperatures like these can kill mountain pine beetles, if it happens at the right time.
But at this point in the winter, it won't do much. The beetles are just larvae and they're perfectly prepared to ride out wicked weather.
"At the moment, the mountain pine beetle is mostly going to be at its most tolerant stage in terms of cold. This is because as the winter begins, as it progresses, the beetles gradually produce antifreeze in their blood," said Allan Carroll, a forestry professor at the University of British Columbia who studies Alberta's management of mountain pine beetles.
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The beetles burrow in pine tree bark, devastating boreal forests. Infestations have brought down more than 16 million hectares of B.C. forest, and have begun destroying huge swaths of Alberta's boreal habitat.
Come spring, the beetles metabolize the antifreeze and are more susceptible to the cold, so the timing of a cold snap is critical in decimating their populations.
If December's extreme cold happened earlier in the year, or in March when the beetles are more mature, they likely wouldn't stand a chance, said Nadir Erbilgin, a forest entomologist at the University of Alberta. But temperatures at that time need to drop below –40 C for at least a week to kill about 99 per cent of an infestation, he added.
The insects likely survived the most recent cold snap just fine, he said, but the impact of the cold won't be known until the insects mature and emerge this summer.
"I cannot be certain ... [but] I'm optimistic it has some impact," he said.
Up to 80 per cent of pine beetles don't survive winter
There was an outbreak of mountain pine beetles in Western Canada in the 1970s that ended in the 1980s. In 1984 and 1985, severe cold weather came at the end of October and beginning of November, before the beetles were prepared. It slashed their populations, Carroll said.
Around 70 to 80 per cent of beetles die in the winter of various causes, even in the healthiest population, Carroll added. Relying on the weather to control the beetle population just isn't practical, he added.
The government of Alberta has spent nearly half a billion dollars on controlling the spread of the beetle since 2006, Carroll said. This involves cutting down and destroying infected trees in an effort to slow their spread.
Carroll said he just finished a study into whether the government has succeeded. He says it has, but doesn't believe the mountain pine beetle will ever truly be eradicated in Alberta.
"The mountain pine beetle has been expanding its range since the last glaciation," he said. "And the recent warming with climate change has given it a helping hand to get across the Rocky Mountains and invade the pine forests of Alberta."