Nature Center to utilize wasps to battle EAB

Published 5:50 pm Tuesday, June 20, 2023

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Will be the first biological control of the Emerald Ash Borer in Mower County


The City of Austin has gained a new tool in its fight against emerald ash borer (EAB). 

The Jay C. Hormel Nature Center has partnered with the Minnesota Department of Agriculture (MDA) and the US Department of Agriculture (USDA) to become the first biological control, or biocontrol, site for EAB in Mower County. 

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Biocontrol uses tiny parasitoid wasps, which are natural enemies of EAB, to help manage infestations. The wasps have no stinger and are host-specific to EAB, meaning they cannot complete their life cycle without the larvae or eggs of EAB, so there is little to no risk to humans or the environment.

The largest of the wasp species used in biocontrol is about the size of a mosquito while the smallest is the size of a small ant. 

The MDA selects biocontrol sites that meet several criteria set by the USDA. They need at least 40 acres of continuous wooded land with substantial ash populations (≥25% ash) that will be protected from harvesting or development for at least five years, limited human activity, and a confirmed EAB population. The Jay C. Hormel Nature Center is an ideal place to implement biocontrol in Mower County. 

The goal of biocontrol for EAB is to establish a stable population of parasitoid wasps over several years of releases and monitoring by the MDA. 

Once established, the wasps can reproduce and help reduce the number of EAB infestation and killing ash trees. A study conducted in Michigan by the USDA showed that the wasps killed 20-80% of EAB in ash trees.

EAB is an invasive beetle that feeds on ash trees. Larvae of the beetle kill ash trees by eating the outermost layers of wood containing nutrients and water, effectively starving the tree. It is always fatal to Minnesota’s native ash trees, with most trees succumbing to an infestation within 5-7 years. 

There are nearly one billion ash trees in Minnesota, the highest amount in any state, the majority in naturalized settings like the Jay C. Hormel Nature Center. EAB was first confirmed in Mower County in 2020. The Jay C. Hormel Nature Center along with all of Austin was confirmed to be infested in 2022.

The public is invited to the release of the wasps at 2 p.m. Thursday to experience a release of the wasps used in biocontrol and learn more about this opportunity for the Jay C. Hormel Nature Center.