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2002 Research Grant Recipient - Jennifer Hiscott

Curbing the purple peril
In the 1990s, an army of European beetles was intentionally unleashed at more than 200 sites across Ontario in an effort to stem the spread of purple loose-strife, the “zebra mussel of the wetlands.” Since then, however, there has been little scientific monitoring of the effect of the biological control program on the pretty but invasive Eurasian plant, says Jennifer Hiscott, a student in environmental biology at Nipissing University in North Bay, Ont.

With the support of a research grant from The Royal Canadian Geographical Society, Hiscott has studied the impact of the introduction of the Galerucella beetle, which feeds exclusively on purple loosestrife. Last summer, she surveyed wetlands near Hamilton, North Bay and Peterborough, where the minuscule leaf-eating insects were released in 1993, 1995 and 1997, and discovered that they have had a significant impact on the loosestrife’s ability to produce flowers and seeds. A single plant can yield more than two million air- or waterborne seeds, which explains how loose-strife can spread like a brush fire.

Hiscott’s field studies showed ample evidence of the beetles’ characteristic paper-punch holes in loosestrife leaves. But she was surprised to find that at the site of the most recent beetle release, in Peterborough, there were no flowers and there was a greater amount of grazing. Hiscott had expected the Hamilton location, where the beetles were introduced four years earlier, would have shown more signs of insect damage. “I’m not sure whether the loosestrife [near Hamilton] is starting to defend itself against the beetles,” says Hiscott. She is studying the results of chemical analyses of leaves to find out whether the loosestrife near Hamilton is producing more phenols, the plant’s natural defence mechanism against leaf-eating insects.

In the meantime, Hiscott hopes her research will “add to the scientific evidence around this important ecological issue.” Some scientists are even questioning whether purple loosestrife is as invasive as once thought. “There haven’t been a lot of studies to see whether purple loosestrife is actually displacing native plants from wetlands,” she says.

- Monique Roy-Sole

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