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Canadian researchers save our trees using tiny Chinese wasps

It's been two months since we heard the good news that the Asian Long-horned Beetle had finally been eradicated from Canada, but in parts of Ontario and Quebec, our trees are still under siege by another six-legged invader.

Here's the innocuous-looking little pest, right here. He's the Emerald Ash Borer, and he and his friends have been responsible for the deaths of tens of millions of ash trees in Ontario, Quebec and the eastern United States since they were first spotted in 2002. According to the Canadian Food Inspection Agency, billions more tress across North America are at risk of infestation and death.

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So far, the response to the threat has been mainly the regulation of where ash wood, and firewood in general, could be shipped, because removing the trees didn't seem to be helping. However, research has been underway for the past decade to put a stop to the marauding bugs and, in the new issue of the Journal of Economic Entomology, it seems as though there is finally some hope.

The best bet to take care of the insects, given that eradication 'by hand' is as close to an impossible task as you can get, is through what's known as biological control; think of the old lady who swallowed the spider to catch the fly. Only, ideally, with better results.

Researchers collaborating with Michigan State University and the US Forest Service have at last identified a natural predator of the Ash Borer that seems to be a good candidate — Tetrastichus planipennisi, a tiny, parasitic, non-stinging wasp that's native to China.

It might not look like much, but so far the wasp seems to be making a difference since its initial release in 2007. The little wasp does its beneficial work by laying its own eggs into, or on the Borer larvae, killing it. Authors of the paper observed that, in sites where the wasps had been released near Lansing, Michigan, they were thriving despite not being native to the area. And by thriving, of course, they were going to work on the Ash Borer population at the same time.

While research continues in both the US and Canada, it looks as though we may be onto something with this little wasp.

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So what happens when the wasp finishes killing off the Borers and we're stuck with a plague of wasps instead? Well, one of the reasons the wasp was chosen is that — in laboratory tests, at least — the wasp attacked only actively-feeding ash borer larvae and rejected all non-ash borer hosts. So, presumably, wasp and borer should go together, when they go.

The Emerald Ash Borer is just one of dozens of invasive insect species threatening parts of Canada at the moment. Another notable bug causing uneasiness in Canada's forests (and lumber industry) is the Brown Spruce Longhorn Beetle, currently only present in Nova Scotia and New Brunswick, where management strategies are in place to try to prevent its spread.

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