A New Control Method for Emerald Ash Borer
October 2011
A tiny green insect is wreaking havoc on trees across Canada and the United States. The emerald ash borer has killed millions of ash trees since it was first detected in North America in 2002.
Native to Asia, the emerald ash borer was likely transported to North America in woody material used in shipping containers. Its spread has been facilitated by the movement of firewood and planting stock. To date, the emerald ash borer has been identified in at least two Canadian provinces and 13 U.S. states.
Control options are limited, and forest managers have adopted a management strategy to slow the insect’s spread in several ways: through removing trees, restricting the movement of materials from infested areas, and injecting certain trees with an insecticide.
To help further stem the spread of the pest, researchers at Natural Resources Canada’s Canadian Forest Service (CFS) have turned to a safer, more effective alternative: pheromones, natural compounds or chemical signals that species use to communicate with members of the same species.
By identifying and synthesizing an insect pheromone in the lab, it can then be used to disrupt the insects’ mating cycle or to lure them into traps to reduce insect populations. Since pheromones naturally occur and are species-specific, they are safe and natural pest control mechanisms that pose no danger to humans and other animals.
Unlocking a Chemical Mystery
In a new paper published in Environmental Entomology, CFS insect ecologists Peter Silk and Krista Ryall provide the first evidence of a sex pheromone in the female emerald ash borer that attracts the male.
They found that when the pheromone is placed in green traps with a green leaf volatile — a chemical a tree emits when stressed — the trap catch of male emerald ash borer increased by at least 50% and in some cases up to 100%. By discovering and synthesizing this pheromone, the researchers believe they have uncovered a way to improve detection methods and management tools for the insect.
Pheromone Research a Complex Problem
Pheromone research is highly complex. “We first have to identify the insect pheromone which is not easy considering each insect species has unique pheromones,” says Peter. “And then, to synthesize it we have to break it down chemically, which presents its own challenges because a million millionth of a gram is difficult to detect.”
But these difficulties are all worth the effort. “This pheromone is the icing on the cake of a large body of emerald ash borer research,” says Peter. “By bringing together all of the research done to date by CFS across the country and other organizations, we’re able to test the pheromone in the field under optimal conditions to get maximum trap catch. The results are very positive.”
To learn more about this important research and its important findings, you can read the article. And for more information on the insects and diseases in Canada's forests, visit NRCan’s “Insects and Diseases” Web page.
To read about related articles, see Forest Disturbances
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