Stingless wasps helping in the war against Emerald Ash Borer - KTTC Rochester, Austin, Mason City News, Weather and Sports

Stingless wasps helping in the war against Emerald Ash Borer

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WINONA, Minn. (KTTC) -- Since the emergence of the Emerald Ash Borer in Minnesota in 2009, it has caused major problems to local ash trees. In the past few years, stingless wasps have been released to fight the ash borers. More are going to be released in Winona soon and there's now evidence the wasps are doing their jobs.  Before these stingless wasps were brought over, there were no known predators to the Emerald Ash Borer. That changed in 2011 at Great River Bluffs State Park when wasps were released with the idea that these wasps would lay their eggs in the EAB larvae, killing it. But would it work? 

"We know that is isn't going to eliminate the Emerald Ash Borer, but hopefully it can slow it down a little bit," said Tree Care Adviser Nancy Reynolds.

The plan that may have seemed far-fetched in its infancy seems to be working. In September 2011, stingless wasps were released at Great River Bluffs State Park in the hope that it would rid the park of EAB and save the ash trees there.

"Specifically what the wasp does, it's called a parasitoid, and so it lays its eggs either on or in Emerald Ash Borer life stages and as part of their development, they devour and kill the Emerald Ash Borer life stage," said Minnesota Department of Agriculture Entomologist Mark Abrahamson.  

That's what happens in Asia where both species are from. Great River Bluffs State Park Manager Rick Samples said that's happening here. They have found wasp eggs in the EAB larvae. Samples also said that the stingless wasps have migrated about a half of a mile away from the release site, further providing evidence that the wasps are thriving off of the EAB larvae.

"If they can move a half of a mile, that's a huge distance for them, and so that's really promising to know that they're reproducing and that they're moving with the Emerald Ash Borers," said Reynolds.

With proof that this method is working. The Minnesota Department of Agriculture has taken this fight to downtown Winona, and plans to release more wasps this week to add to the thousands of stingless wasps already released this year in the county. 

It's not just wasps fighting the pest. Our harsh winter this past year aided in the wasps effort at Great River Bluffs. Samples says they found dead Emerald Ash Borer larvae underneath the bark of ash trees that did not have wasp eggs in it, indicating the Minnesota cold got the best of the ash borer.

The wasps that are attacking the ash borer pose no threat to humans or other wildlife. As of right now no adverse effects have been found due to the stingless wasps being here. Winona is also using chemicals on some of the city's ash trees to prevent damage from the ash borer.
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