Will this invasive insect feast on Ontario’s forests?

May 27, 2016

By: TVO.org

Ontario’s lush northern forests could be the next feast for an invasive insect following the path created by the warming climate.

A native species in British Columbia, the voracious mountain pine beetle is poised to move into Ontario’s vast boreal forest where researchers fear they could replicate the massive tree die-offs first witnessed in B.C. and Alberta.

The black beetle, about the size of a grain of rice, has taken advantage of a shifting climate to radically reshape the forests of Western Canada. Typically kept in check by extended periods of cold winter weather below -35 C, the beetle has thrived in warmer temperatures, allowing it to devastate mature lodgepole pines by laying eggs beneath the bark and starving the tree of nutrients. Needles turn red and grey before falling off within four years.

Free of predators in warmer weather, the beetle’s population—and its appetite—has soared. British Columbia has lost anestimated 18 million hectares of forest out of 55 million since the early 1990s. And the warming trend that allowed the mountain pine beetle to flourish? Coupled with the beetles’ newfound taste for jack pine, a primary tree in Canada’s boreal forest has researchers worrying it will give the beetle all the power it needs to spread east.

“It’s an outbreak on a national scale,” says Tracey Cooke, executive director of Ontario’s Invasive Species Centre. Cold winter temperatures traditionally killed large swaths of the mountain pine beetle, but the population has grown as the winters turned milder. And it’s moving, following the front of the changing climate and crossing provincial boundaries.

“The insect has since expanded its range into northern and central Alberta so that it is now within 50 kilometres of the Saskatchewan border,” Cooke says. While mountain pine beetle is native in western North America from Mexico to the Alaskan border, the insect would be considered invasive as it eats its way through the 10,000 kilometre-long boreal forest. And while some woodpeckers enjoy eating the beetle, the scale of the infestation is well beyond what natural predators and parasites can control.

Warming temperatures increase stress on ecosystems and trees, Cooke says, making them susceptible to attack from invasive species. There are also fewer deep freezes, which traditionally have killed off some invasive species. “Under a changing climate, it is generally expected that there will be increased frequency, severity and size of forest insect outbreaks.”

Yet greater public awareness won’t stop the mountain pine beetle from continuing its relentless eastern sweep. Researchers from the Ontario government have already partnered with western provinces, Natural Resources Canada, the Canadian Forest Service and the University of British Columbia to produce a national risk assessment on the potential for mountain pine beetle to ruin forests from B.C. to Newfoundland and Labrador.

The national risk assessment, drafted under the auspices of the Forest Pest Working Group of the Canadian Council of Forest Ministers, has found that no climatic or biological barriers exist to limit the eastern spread of mountain pine beetle.

Ontarians can breathe a little easier knowing the beetle’s movement has slowed considerably in eastern Alberta. “While this suggests it may be years or even decades before mountain pine beetle might invade Ontario,” notes Ministry of Natural Resources and Forestry spokesperson Jolanta Kowalski in an email, “it would be prudent for Ontario to be prepared.”

Beyond passing the Invasive Species Act in 2015 and completing an Ontario-specific risk analysis, the ministry conducted a mock exercise with mountain pine beetle-trained foresters to test the ministry’s response to a theoretical invasion. Using satellite imagery and a scenario whereby mountain beetle pine arrived in Ontario via imported logs, their objective was to eradicate a localized, isolated infestation.

“The response actions included aerial and ground surveys to detect and delineate the size of the infestation,” Kowalski said, “cutting and burning of infested trees and a local quarantine to restrict the movement of infested pine material outside the area.”

The province is also responding to the impending beetle threat in the lab. As a partner in TRIA-Net, a network of pine beetle researchers and insect population modellers from provincial and federal governments and academia, Ontario is examining the beetle’s genetics and the fungi it carries to investigate potential weaknesses that may be exploited.

Conducting eastern Canadian beetle research is vital. Forests in British Columbia and Alberta are markedly different from those in Ontario that grow under different climate and soil conditions and fire regimes. The tree species make-up is also different. Kowalski said, “The insect’s behaviour in British Columbia may not be reliable for predicting what the insect will do if it continues to move eastward.”

By: TVO.org

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