The Minnesota Department of Agriculture is teaming up with the University of Minnesota and the U.S. Forest Service to combat the emerald ash borer.
Scientists are researching stingless wasps, which are predators of the destructive beetle. This research, which started in 2010, focuses on the flight distance of the stingless wasps as well as how both species tolerate cold.
"The wasps are fussy eaters -- not only do they only like EAB (the emerald ash borer), they can only eat EAB," said Brian Aukema, an assistant professor at the University of Minnesota who studies the flight distance of wasps. "It's convenient for us and other insects, not so convenient for EAB."
The emerald ash borer was discovered in Detroit in 2002 and spread to the Twin Cities by 2009, according to Aukema.
Its larvae live in the bark of a tree and feed on it, killing its vascular system. The adult emerald ash borer eats only foliage, said Rob Venette, a biologist with the Forest Service's Northern Research Station in St. Paul.
Aukema is measuring the flight distance of the predatory wasps, which he said are the size of a grain of rice. They are tethered to a tiny wire and set at a pivot point between two magnets. The wasps fly in circles as a computer calculates distance. Aukema has found that some wasps can fly 5 miles in a day.
Venette is measuring the "cold hardiness" of prey and predators. Lab tests include putting wasps and borers in freezers to determine the temperatures
Venette said the wasps are more tolerant of the cold than the emerald ash borer so the wasps can go wherever the beetles are found.
Field testing of emerald ash borers started in winter 2009 to 2010: in Great River Bluff State Park outside of Winona, which is the warmest location; St. Paul, which is in the middle range; and Grand Rapids, which is the coldest.
Venette said 90 percent of emerald ash borers were killed in Grand Rapids, which reported temperatures of about minus-25 degrees.
These beetles have killed tens of millions of trees nationally, according to Mark Abrahamson, an entomologist for the Minnesota Agriculture Department. Locally, 1,000 to 1,500 trees have been infested in the Twin Cities and southeastern Minnesota.
The biological control project is funded by a $500,000 grant from the Minnesota Environment and Natural Resources Trust Fund.
Katie Wielgos can be reached at 651-228-5591. Follow her at twitter.com/kwielgos.