Who says you can't fool Mother Nature?

It certainly isn't Dezene Huber, a PhD student in Simon Fraser University's department of biological sciences. He's part of a research team investigating the secret scent life of two of British Columbia's most destructive forest insect pests.

His goal? To fool the insects into bypassing vulnerable trees.

For the past two years, Huber has been studying how two species of bark beetle - the Douglas fir beetle and the mountain pine beetle - find the trees they need to survive in a mixed forest environment. The answer is in the air - in natural scents given off by the beetles, and, surprisingly, by the trees themselves.

These two species of bark beetle are tiny, about half a centimetre long, and attack their preferred host trees - Douglas firs and lodgepole pines - by tunnelling under the bark and laying eggs. They eventually girdle and kill the trees, destroying billions of dollars worth of commercial timber in B.C. every year. It's long been known that bark beetles use chemical signals, or pheromones, to attract others of their kind to a suitable host tree. It's also known that they can detect the scent of host trees. But Huber's work reveals that the beetles are doing much more. They're smelling other trees in the forest, too.

Every type of tree, says Huber, releases signature compounds, or 'volatiles,' into the air. And just as we can smell the fragrance of a nearby pine or fir, a bark beetle can sort through the scent bouquet of a mixed forest to find the tree that it wants.

The beetles can't afford to make a mistake. Burrowing into the wrong tree not only wastes time, but the strong defences of non-host trees, such as toxic resin, can kill adult beetles and their young.

"We think that, as a beetle flies through the forest, it smells a non-host tree before it even gets to it, and the message is to keep on going," says Huber, who has hacked down trees su
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Contact: Valerie Shore
valerie_shore@sfu.ca
604-291-3219
Simon Fraser University
28-Nov-1997