The iconic tree of the north, depicted by painter Tom Thomson on a windswept isle in Georgian Bay, is threatened by a creature not much larger than a pencil tip.
A bug barely the size of a grain of rice has burst out of British Columbia and now threatens the entire boreal forest clear to the Atlantic coast.
The mountain pine beetle, Dendroctonus ponderosae, is native to North America. In British Columbia, they infested lodgepole pine, Pinus contorta var. latifolia, and larvae spending winters under the bark of mature pines. Until the late twentieth century, the pest was largely controlled by the harsh winters of the provincial interior. Then climate change stepped in with devastating effect.
Repeatedly warmer winters failed to kill the larvae. Starting in 2000, beetle populations began rising explosively. The needles of infested lodgepole pine turned red. Worse, the timber was unsalvageable, the wood stained blue thanks to a fungus carried by the bugs. Vast areas of interior B.C. were affected, with the dead trees offering fuel for fires that swept through forest communities.
By 2009, the bugs had breached the barrier formed by the Rocky Mountains, wafted by westerly winds into Alberta. There a fresh menace presented itself. The mountain pine beetle first crossed a wide swath of forest where lodgepole pine and jack pine, Pinus banksia, interbreed to create hybrids trees.
Jack pine, the arboreal emblem of Northwest Territories, is the northernmost pine species. Usually a short-lived, small and tough tree it is the principle species found in Canada’s vast boreal forest. Typically, it colonizes dry, sandy areas after forest fires since it requires the heat from such to open its cones. French-Canadian lumberjacks believed any woman who passed close to one would become permanently sterile like the closed cones.
Late in 2009, Ted Morton, Minister of Alberta’s Sustainable Resource Development, warned what might happen next. And happen it has. The hybrids lodgepole pine crossed with jack pine offered pastures anew for Dendroctonus ponderosae. A nifty piece of laboratory research by tree biologists and geneticists at the University of Alberta confirmed the worst scenario: mountain pine beetles had successfully jumped species from its main host, the lodgepole pine, to the jack pine.
The discovery was large due to the work of University of Alberta molecular ecologist Catherine Cullingham, first author of a paper published online 4 April in the journal Molecular Ecology. According to the university, the insects have been found in jack pine as far east in Alberta as Slave Lake, which is 200 kilometres north of Edmonton. In Professor Janice Cooke’s words, the bugs are knocking on Saskatchewan’s door.
Just how devastating a threat the mountain pine beetle poses is problematic. Scientists are stymied for lack of research, as the jump in species is so recent. One thing is for sure though: the iconic tree of the north, depicted by painter Tom Thomson on a windswept isle in Georgian Bay, is threatened by a creature not much larger than a pencil tip.
Wes Porter is a horticultural consultant and writer based in Toronto. Wes has over 40 years of experience in both temperate and tropical horticulture from three continents.
