Rethinking the pine beetle

Rethinking the pine beetle

Now that the mountain pine beetle has affected almost 15 million hectares of British Columbia forest, Joerg Bohlmann hopes to save the rest of Canada from the same fate
January 21, 2010
The life cycle of the mountain pine beetle.
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The life cycle of the mountain pine beetle.
Alberta Sustainable Resource Development

When he talks about the fight against the mountain pine beetle, Joerg Bohlmann likes to use a medical analogy. “Imagine we’re trying to combat malaria,” says the genome biologist based at the University of British Columbia, “but we don’t know the makeup of the disease-causing parasite, so we leave it out of the equation. We just look at the mosquito and humans. We’re missing an essential part of the triangle.”

Until now, the research conducted on the mountain pine beetle, which has affected nearly 15 million hectares of lodgepole pine forest in British Columbia and is threatening to spread across Canada, has largely focused on the tree and the beetle, but not so much on a pathogenic fungus that works in symbiosis with the beetle. The fungus rides with the beetle to new host trees and then makes the nutrients in the tree more accessible to the beetle. Together, they kill the tree. “Is it really so different from a human disease system?” asks Bohlmann. “No, it’s not.”

After mountain pine beetles mate, they form
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After mountain pine beetles mate, they form vertical tunnels, or galleries, under the tree bark where they lay their eggs.
Brytten Steed, USDA Forest Service; Bugwood.org

In medical science, researchers investigate the biology and genomes of infectious diseases to find the right treatment. The same, says Bohlmann, goes for forest research. To apply the same rigorous approach to the pine beetle infestation, Bohlmann co-founded The Tria Project, which brings together a diverse group of scientists from several universities in British Columbia and Alberta and from the federal and provincial forest services, with support from Genome British Columbia, Genome Alberta and Genome Canada. “This is one of the first times a large-scale effort is being made to approach a forest disease system with the same molecular and genomics tools the biomedical world has used for at least 20 years,” he says.

The broad scope and national interest in The Tria Project hint at the potential magnitude of the mountain pine beetle infestation. The beetle has crossed the geographic barrier of the Rockies, and the pan-Canadian boreal forest lies in its path. “The floodgates are open,” says Bohlmann. “There is no barrier. We can’t predict with any level of certainty what will happen until we have more knowledge of the disease system in a new environment.”

A scanning electron microscope image shows O.
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A scanning electron microscope image shows O. clavigernum, the pathogenic fungus that works in symbiosis with the mountain pine beetle to kill trees.
Adrianne Rice, Natural Resources Canada-Canadian Forest Service; George Braybrook, University of Alberta

Part of the research in Bohlmann’s and his colleagues’ labs focuses on understanding the chemical signals given off by the pine trees, the beetles and the fungus. For the beetles to mass attack a tree and for the fungus to hitch a ride, these organisms must communicate with one another. If one can interrupt those communication signals, it may be possible to weaken the beetle-fungus one-two punch.

Other researchers are using the genomic information Bohlmann and his colleagues are collecting to identify resistant seedlings and to understand how the beetle spreads and how trees fight the pathogens. Because some lodgepole pines are genetically more resistant to beetle attacks, researchers like forest geneticist Alvin Yanchuk of the BC Forest Service may be able to use this genetic information to select these traits to grow resistant pine seedlings. “The Tria Project is giving us a much better background into the genetics of the trees,” he says. “This is not new. Applied genomics is now being used with animals and crop plants. It’s just new to managed forests.” Half of the trees now planted by forest companies in British Columbia come from the BC Forest Service’s selectively grown seedlings.

An adult mountain pine beetle excavates a larval
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An adult mountain pine beetle excavates a larval gallery.
Whitney Cranshaw, Colorado State University; Bugwood.org

It will likely be another century before B.C. forests will face a similar mountain pine beetle epidemic, but the rest of Canada is learning all it can from The Tria Project. For Yanchuk, the research from Bohlmann and his colleagues is far-reaching, “Tria,” he says, “is a good model for how we will look at forest pests in the future.”

Related AAAS Science Magazine article