Canada to Import Parasitic Wasps to Battle Emerald Ash Borer Infestation

To battle a type of beetle devastating to native ash trees, the Canadian government has approved the import of two types of parasitic Chinese wasps in a plan to save the country's trees.

While adult Emerald ash borers are fairly harmless, simply munching on ash trees' leaves, their larvae are detrimental to ash trees in North America, burrowing into the bark quickly enough to kill a tree within a year.

The U.S. Department of Agriculture reports that Emerald ash borers have destroyed tens of millions of ash trees. Similarly, Canada's department of natural resources reports the Emerald ash borer has "killed millions of ash trees and continues to spread into new areas."

To combat the tree-eating beetles, the Canadian Food Inspection Agency approved the import two stingless Asian wasps, Tetras-tichus planipennisi of the eulophid family and Spathius agrili of the braconid family, according to The Windsor Star, which covers an area in Canada where the beetles were first reported.

Using wasps to combat the Emerald ash borer is already underway in 14 U.S. states. In Michigan, the same two wasp species have been deployed as ash borer defense and have seen favorable results, the Star reports.

Native to Asia, the Emerald ash borer was first recorded in North American in 2002 and has spread throughout much of eastern Canada, the Midwest and Atlantic Midwest. The beetle has no natural predators in North America, so introducing the predatory wasps is viewed as a solution for a difficult problem, though officials must consider the effects the introduced wasps will have on other native species.

"You have to be careful with these. You have to do appropriate background testing first, to make sure (the wasp) is not going to attack native beetles," invasive species expert Hugh MacIsaac of the Great Lakes Institute of Environmental Research said to the Star. "But these types of introductions have worked previously."

People living where Emerald ash borer at present are being encouraged not to move firewood - a favorite home of the beetles - and to burn it where they buy it. But despite public Emerald ash borer campaigns in the United States and Canada, the beetle is still spreading like a wildfire.

Bill Roesel, a forester in the city of Windsor, told the Star that without introducing wasps the invasive beetle would be "unstoppable."

"The Emerald ash borer could move across North America and wipe out almost every ash tree on the continent. It's certainly one of the worst insect invaders we've ever had," he said.