Alberta's cold snap was good news in the fight against mountain pine beetle

Mountain pine beetle larvae are shown in Twisp, Wash., Oct. 14, 2011. (The Seattle Times, Steve Ringman)

EDMONTON — Albertans may have survived last week's extreme cold snap, but experts are hoping mountain pine beetles did not.

In recent years the tree-killing pests invaded the forests of Jasper National Park, leaving red, dead pines in their wake, and have since moved into communities like Hinton and Sundre.

The problem has been an economic hardship for Canada's forestry industry, with millions of square kilometres of forest succumbing to the bugs in the past decade.

The bugs are hardy and multiply quickly, taking off each season in search of fresh trees to munch on.

But they have one weakness: extreme cold.

"WE SAW A LOT OF MORTALITY"

"They're not all dead, but we saw a lot of mortality, we saw a lot of winter kill in that short but intense cold snap that we suffered through last week," said Janice Cooke, a University of Alberta biological sciences professor.

Temperatures in Jasper, Hinton and Sundre — key battlegrounds in the fight against pine beetles — dipped below -40C a couple of times during the cold snap.

Cooke said early projects show it might have been enough to kill more than 95 per cent of pine beetle larvae.

Larvae make their own "antifreeze" in the winter to survive cold temperatures, but they still can't cope when temperatures plummet so dramatically.

"It was so intense that even some of those bigger guys seem to have succumbed to the cold, so we're very encouraged by the model output that came out over the weekend," said Cooke. "We're lucky so far that we've had a good killing year last year. This year we're getting another good cold snap, so two years running we're knocking those populations back."

It buys time for the province to enact further control measures such as falling and burning affected trees. Back in October, Alberta's Ministry of Forestry announced a $5-million boost for the pine beetle management program through 2022-23.

Caroline Whitehouse, a forest health specialist for the ministry, said it typically takes a few years of large-scale cold events to cause notable mortality rates in pine beetles.

"Beetles, especially when they’re outbreaking, they’re really quite resilient, so these cold effects, it’s great if they really impact smaller populations because then you can see the effect much more quickly," she said. "Whereas at a large outbreak, it can take us a little bit more time to see and recognize it.”

MOVING EAST

Pine beetles have been spotted across the province of Alberta and as far east as the western edge of Saskatchewan.

"You get the slow trickle of beetles moving from stand to stand through the years, but every once in a while a portion of the beetles will fly long distances, but those are the ones we saw show up in some of the rural areas around Edmonton, south and southwest of Edmonton," said Mike Undershultz, a senior forest entomologist.

Homeowners can manage beetles by cutting and burning any infested trees to prevent them from spreading to adjacent trees. Undershultz says there are also commercially available chemical pheromones like verbenone that repel beetles from tree stands.

The forestry ministry says it won't know for sure how many pine beetles died during the cold snap until ground surveys are complete later this summer.