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Beetles infesting jack pine forests

The mountain pine beetle is now infesting Alberta’s jack pine, say scientists, which means it could spread through forests across Canada.

The mountain pine beetle is now infesting Alberta’s jack pine, say scientists, which means it could spread through forests across Canada.

University of Alberta researchers recently released a paper that provides the first proof that mountain pine beetles have made the jump from lodgepole pine to jack pine trees in Alberta.

Mountain pine beetles are black, rice-sized beetles that bore into lodgepole, ponderosa, whitebark, limber, Scots and now jack pine. Fungi carried by the bugs chokes the tree to death, turning its needles red and its wood blue. The province has spent millions battling the bugs ever since they arrived en masse from B.C. in June 2006.

Lodgepole and jack pine are closely related, says St. Albert retired forestry professor Peter Murphy, and might even have been one species in the distant past. Their ranges meet in Alberta, with lodgepole pine in the west, jack pine in the east and a zone of hybrid trees in between.

Researchers have long suspected the bug could infest both species in the wild, says Janice Cooke, professor of biology at the University of Alberta and one of the study’s authors, but couldn’t tell since the trees looked so alike and often interbred.

Her team used pole pruners and shotguns to collect branch samples from the tops of infested Alberta trees for DNA analysis. That analysis confirmed that the beetles had infested both jack pine and jack-lodgepole hybrids. “The mountain pine beetle is knocking at the door of jack.”

This confirms what the province has suspected for years, says Duncan MacDonnell, spokesperson for Alberta Sustainable Resource Development. “The beetle can travel in jack pine all the way from Alberta to Labrador,” he says. “This is the frontline of what could be a national battle.”

Bugs on the march

Jack and lodgepole pine are tough to tell apart unless you’re a trained forester, Murphy says. Lodgepoles are generally tall and thin with longer needles, while jacks are stubbier with shorter needles.

The Rocky Mountains originally kept the bugs in B.C., Murphy says, but they swarmed and blew over them. Cold winters were then supposed to keep them in check, but those have been few and far between. Now that the bugs are in jack pine, there’s essentially no habitat barrier to keep them from spreading across the nation.

The beetle has now spread to the Slave Lake region, Cooke says, which puts it within about an hour’s drive of Edmonton. There are jack and lodgepole pine near the city, but they don’t appear to be infested yet. “We should all be vigilant.”

Teams chopped down 170,000 trees this winter around Grande Prairie in order to slow the spread of the beetle, MacDonnell says. Researchers will now survey the forests to see how many survived the winter.

The study wouldn’t change the province’s strategy on the ground, MacDonnell says. “We’re taking out infested trees. We don’t really care what kind of tree (the bug) is in.”

It’s hard to say how the bug will spread from here, says Catherine Cullingham, a molecular ecologist at the U of A and lead author on the study.

“We don’t know much about the bug’s reproduction rates in jack pine, for example, or how climate affects it. Jack pine is also more spread out than lodgepole, which could limit the bug’s population. It could be really, really bad, or it could be not so bad.”

Jack pine is a keystone species in the boreal forest and important for the forestry industry, Cullingham says. “If its distribution is affected by the mountain pine beetle … it could have a really big impact.”

The study is available in Molecular Ecology.

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