The Minnesota Department of Agriculture (MDA) is using innovative research from the University of Minnesota and the U.S. Forest Service to help determine the next steps against emerald ash borer (EAB). The Forest Service is the first in the nation to study the insects’ cold tolerance, and the University is leading the way in studying flight distance potential of EAB biological control agents.
MDA started EAB biological control in Minnesota in 2010. The strategy seeks to control EAB populations through introductions of EAB’s natural enemies – stingless wasps that prey on the tree pests. Rob Venette, a biologist with the Forest Service’s Northern Research Station in St. Paul, is leading studies of EAB cold hardiness as well as the hardiness of three species of stingless wasps to determine the insects’ potential range.
“Collaboration among the University of Minnesota, the MDA and the Forest Service is benefitting our research,” Venette said. “We are excited to be contributing to the MDA’s work to control the spread of EAB.”
Sam Fahrner is a U of M graduate student working with Assistant Professor Brian Aukema to study the distance stingless wasps can fly. Fahrner’s research incorporates an unusual machine called a flight mill. The device allows an insect to fly while attached to a tiny wire. The flight mill is connected to a computer, which tracks the distance the stingless wasps can fly. The mill Fahrner uses can track up to 32 stingless wasps simultaneously.
These studies are funded by a grant from the Minnesota Environment and Natural Resources Trust Fund as recommended by Legislative-Citizen Commission on Minnesota Resources (LCCMR). According to MDA Biological Control Coordinator Monika Chandler, the researchers’ work will be important in helping direct biological control efforts against Minnesota’s EAB infestations.
“We will use the cold tolerance information to determine where to release each stingless wasp species,” Chandler said. “Knowing how far the stingless wasps can fly will help us decide how to allocate the stingless wasps among EAB infestations. Using this research to guide implementation is our best chance for success.”
EAB is a destructive tree pest found in in 18 states, including Hennepin, Ramsey, Houston and Winona counties in Minnesota. EAB larvae kill ash trees by tunneling into the wood and disrupting the flow of nutrients. The metallic-green adult beetles are a half inch long, and are active from May to September. Signs of infestation include increased woodpecker activity, D-shaped exit holes in ash bark and serpentine tunnels under the bark.