Biological Pest Released to Control Emerald Ash Borer

Earlier this summer the deadly Emerald Ash Borer was discovered in three North Carolina counties, and just last week discovered in a fourth county. All four counties, Person, Vance Granville, and now Warren County have quarantines on raw ash wood products. Kelly Oten, forest health specialist in western North Carolina with the NC Forest Service, explains how destructive this pest can be:

“We are the 20th state to find emerald ash borer in our natural forest. All of the other states that have had it have already seen significant ash mortality. Granted a lot of them have a lot of pure stands of ash and we don’t have that, but it is a significant component of our eco system. We have an estimated 258 million ash trees in this state and the borer has the potential to kill all of them.”

As Oten mentioned, mortality rate among ash trees is 100%, and the ash borer works very fast:

“Our best guess is 3-5 years. Its hard to say because when a tree is first attacked you don’t notice it at first. You may see some branches dying but the tree generally looks like its experiencing drought. By the time we see the symptoms, the emerald ash borer has already been attacking the tree for years.”

But the NC Forest Service isn’t idly standing by, last week Oten released three flights of a parasitic wasp into the affected areas:

“We are taking a route that 16 other states have already taken. Its implementing what naturally controls the borer in its native range. Releasing these parasites, they can help keep the borer populations down.”

Oten explains how the forest service will know the wasp is becoming naturalized and effective against the ash borer:

“We will go back to each site where we release them and try to recapture them, actually the offspring of the wasps we released. That would tell us that we are being successful. The wasps are reproducing and controlling the borer. But it will take a while for them to control the levels of the borer.”

These parasitic wasps, mailed from a USDA lab in Michigan, are native to parts of Asia. Oten explains they won’t become kudzu with wings:

“Because its not a native wasp, it can raise some red flags for environmentalists. But anytime the USDA releases non-native insects for a biological control program it does go through rigorous testing to make sure there will be no impact.”

Oten says the parasitic wasp is not considered a cure, but a control mechanism:

“We still may see ash mortality, but the goal is to slow it and start moving toward a more complete management of this pest.”

Forest health specialist in western North Carolina with the NC Forest Service Kelly Oten.


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