ShareThisBy MARK HUME
Toronto Globe and Mail
The small beetle that has already eaten its way through about 40 percent British Columbia's lodgepole pine forest since 1993, is developing new appetites.
Researchers at the University of Northern B.C. in Prince George say the pine beetle, is now killing spruce trees as well.
"There were rumors before that pine beetles were not only killing spruce but successfully reproducing in spruce, and we have now observed that in Prince George and we have been trying to document what's going on," Staffan Lindgren, a professor of ecosystem science at UNBC, said this week.
Lindgren said that while the pine beetle appears to be branching out, creating even more of a threat to B.C.'s beleaguered forests, it doesn't point to an ecological disaster on the scale of the current attack. If adaptation does occur, as it appears to be, it will happen slowly and the new beetles initially would likely attack only weak spruce trees.
"I don't foresee any risk to the spruce forest that would be immediate. But that's not to say that we couldn't see something in the long term that potentially could do (what the pine beetle has done)," Lindgren said.
He said the pine beetle appears to be involved in a "speciation event," in which a new type of beetle is evolving.
"Over a long period of time, if we get a speciation event, we essentially get a mountain pine beetle biotype, or new species, that focuses on spruce," he said.
Pine beetles have long been known to attack spruce trees, but the chemical composition of spruce -- which contains the main volatile ingredient used in turpentine -- has been able to kill off the invading insects.
Lindgren said pine beetles now appear to be developing a resistance to the harsh chemical environment in spruce and are able to breed and multiply to such numbers that they can kill the trees.
Researchers don't yet know whether pine beetles have killed any healthy spruce trees, or whether all the victims have been dead or dying. This summer investigators are "baiting" some healthy trees to attract beetles so they can monitor the results.
Lindgren said UNBC researchers first became aware some pine beetles were shifting to spruce last summer when it was noticed that spruce trees were dying along with pines around the city.
Lindgren thinks the phenomenon is occurring because of the massive numbers of pine beetles in B.C.'s forests.
"It's possible that huge outbreaks like the one that we're experiencing now may provide the conditions by which speciation can occur in insects like this," he said.
In any given pine beetle population there are bound to be a few insects that are better adapted to dealing with spruce trees. Because of the pine beetle epidemic there are now enough of those beetles that they are able to start breeding.
"There have been studies that suggest we've had these kind of host switching events in the past," Lindgren said.
He gave as an example a subspecies of pine beetle that is believed to have evolved from spruce beetles. That insect feeds only on stumps or downed lodgepole pine.
