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NNSL Photo/graphic

Scientists have hatched a plan to combat the parasitic birch leaf miner (above) with wasps harvested from south of Great Slave Lake. - photo courtesy of Chris MacQuarrie

Bug warfare coming to capital

Andrew Raven
Northern News Services

Yellowknife (Aug 04/06) - Yellowknife has become the newest testing ground in a man-made battle of the bugs.

An Edmonton-based scientist released an armada of wasps last month to combat the troublesome birch-leaf miner, an insect running roughshod over the capital's birch trees.

Researchers hope the experiment in insect warfare will translate into a perennial cure for northern towns overrun by the miner, which leaves fronds looking brown and worn.

"Once the parasite is established in the North, there is nothing (native to the region) to stop them," said Scott Digweed, a scientist with Natural Resources Canada.

Enter the Lathrolestes Luteolators wasp.

The stingerless, four-millimetre-long insect is the perfect natural control for the miner, said Digweed. The wasp deposits its young inside miner larvae. As the wasps grow, they consume the larvae from the inside out - a nasty end for the miner, but a wonderful biological interaction for officials looking to halt to miner infestation.

"They are everywhere," said senior city manager Andrew Morton this week, talking about the explosion of the miner population. Morton has been working with Digweed to find a solution to the epidemic.

Native to Europe, the miner was introduced to North America around the turn of the century and the insects quickly spread across the continent. They likely piggy-backed to Yellowknife on vehicles loaded with birch trees, said Digweed.

Within a few years, the miners spread across the capital area, infesting backyards and public lots. While they are most common in the downtown core, Digweed has found them at Reid Lake, 70 kilometres northeast along the Ingraham Trail.

While a miner infestation is not usually fatal, they leave birches looking like fall has come months ahead of schedule. "If you have a tree, for cosmetic reasons it's not very nice," said Morton.

The challenge so far, has been establishing a healthy wasp population that can survive a Yellowknife winter, said Digweed. He released 160 of the insects July 20, after transporting them, in a cooler, from Hay River. That total is nearly twice the number of wasps freed during 2004 and 2005, the two previous years Digweed conducted the experiment.

"This year, we have the best chance of getting the wasps established," he said.

Researchers are not sure how long that process will take, though. "It's almost impossible to say," said Digweed. "It could be four or five years, or it could take longer."

Once the wasp numbers are up, Digweed plans to haul them to Alaska, which is also dealing with a miner infestation.

While the introduction of foreign species to a new environment can be problematic, Digweed said the wasps only feed on miner larvae - a relationship that should not affect the natural balance of the North.

"A lot of research has been done on this," said Digweed. "We made sure there was a one-to-one relationship between the parasite and pest."