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A plague of tree-killing beetles which swept across British Columbia is
threatening to spread east, to the US. North America faces beetle plague By Julian Siddle
Discovery, BBC World Service Beetles tunnel under the tree bark
The Beetles dig tunnels under the bark of the tree CANADA - A plague of tree-killing beetles which swept across British
Columbia is threatening to spread east, to the US.
The mountain pine beetle has killed more than half of all lodge pole
pine in the province and is now active in neighbouring Alberta. Cold winters usually kill off the beetle larvae, but the region has been
warmer than usual in recent years. Scientists say the beetle could attack and kill jack pines, which are
found throughout North America. Beetle rain Mountain pine beetles occur naturally in British Columbia but in the
last few years their numbers have reached plague proportions. Staffan Lindgren, professor of entomology at the University of Northern
British Columbia, says the beetles have now moved on from British
Columbia to neighbouring Alberta.
the Beetles do not totally kill the forest
Tree-killing beetles are moving east "In places in Alberta there were stories of what they call beetle rain,
where under a perfectly blue sky farmers would start hearing what
sounded like rain on their tin roofs," said professor Lindgren. "It turned out it was beetles coming out and falling on the roofs,
literally billions and billions of beetles." Without interference from man, mature lodge pole pine would be regularly
destroyed by forest fires. But, Professor Lindgren explained, the
species has evolved to use fire to aid regeneration. "Lodge Pole pine has a cone that's adapted to fire," he said. "As fire goes through, it kills off all the other species, but actually
aids in opening up the cone, and re-establishes pine as the dominant
species. "We've kept fire out of the ecosystem and created huge areas of mature
lodge pole pine, which are ideal for mountain pine beetle. 'Perfect storm' Although less valuable than spruce or cedar, lodge pole pine has become
a cash crop species, as it grows quickly and is ideally suited for
turning into the "sticks" widely used in the US house-building industry. Jim Snetsinger, chief forester with British Columbia's Ministry of
Forests and Range, said the beetle could be controlled when it was
confined to small areas. But the recent explosion in numbers has meant that the best the forest
industry can do is to salvage the trees already killed by the beetle. A clearcut
Clear cutting is British Columbia's most common method of harvesting timber "The first phase is to detect and monitor the beetles. Second phase is
to harvest affected areas as soon as possible so you can remove the
beetles, and the last phase, which is what we're in at the moment, is to
salvage as much timber as you can before it loses its economic value. "We hit this perfect storm of warm winters, very warm summers and this
large expanse of mature lodge pole pine." he said. As the beetle burrows under the bark of the tree, it secretes a fungus
from its mouthparts which blocks the transport system of the tree. This,
combined with the stress of the beetle attack, kills the tree. Beetle antifreeze In the past, cold snaps before or after winter killed off many of the
beetle larvae, but these have not occurred for a number of years. Dezene Huber at the University of Northern British Columbia is
investigating how the beetle larvae keep themselves alive during the
sub-zero winters. "The insect is generally able to survive at temperatures as low as minus
37C, minus 40C starts to push it," said Dr Huber. "My lab is looking at some of the genes involved in making glycerol, a
particular component of the antifreeze that these larvae use. "We're looking at the larvae in the autumn and the spring to see which
genes are turned on and off in relation to glycerol production." beetle kill wood is of little value The question is, are they going to be able to exploit jack pine to the
same degree that they exploited lodge pole pine?
Dezene Huber-University of Northern British Columbia The damage caused by the beetle, combined with the downturn in the
demand for wood due to the global recession, has brought about a rethink
on forest policy in British Columbia. Mixed forests, rather than monocultures, are now seen as healthier both
for the trees and other plant and animal life - even though a lack of
uniformity makes them more difficult to harvest. Jim Burrows, forest stewardship officer with British Columbia's ministry
of forests and range said: "There's a balance to find in terms of what
we do - whether we should rehabilitate them and just be concerned about
that future crop of merchantable timber, or whether we look at some of
the other values like wildlife habitat." However the threat from the beetle is by no means over. Dr Huber
believes it could spread across North America. "In Alberta, the neighbouring province just to the east, you have lodge
pole pine which they're attacking now, and then after that you have jack
pine all the way across the continent, down through Ontario and even
into places like New Jersey," he said. "We know mountain pine beetles can survive and reproduce in jack pine,
but we don't know how well they can do that. The question now is are
they going to be able to exploit jack pine to the same degree that they
exploited lodge pole pine?"
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