Parasites of the emerald ash borer (EAB) that may help slow the spread of the ash-tree-killing pest have been released earlier this summer in Jefferson and Allamakee Counties as part of a nationwide effort to reduce the threat of this invasive pest.
Additional releases of biocontrol agents have occurred through the summer at Whitham Woods near Fairfield and at Mount Hosmer City Park in Lansing. There has been a total of 10 releases at the Fairfield location. The final release of the season is planned for early October in Lansing. Both the Fairfield and Lansing sites will continue to receive biocontrol releases in 2017, and there are plans for additional release sites next year.
The latest releases in Fairfield included a different species of parasitoid not previously released in the state. Spathius galinae is relatively new on the EAB biocontrol scene (2014) and also uses EAB larvae as its host. Hopefully they will take a liking to Iowa and go to work!
Spathius galinae wasps are more cold tolerate for northern areas like Iowa versus the closely-related Spathius agrili. USDA-APHIS has stopped releasing Spathius agrili in areas above the 40th parallel (northern Missouri) because of failure to establish.
The Spathius galinae adult wasps recently released are much larger than the Tetrastichus planipennisi released throughout the summer. They are similar in size to a mosquito. See the photo below. A total of 629 of the parasites, mostly females, were shipped in plastic cups as seen in the photo for release in Jefferson County.
Read more about biological control of the emerald ash borer on the USDA website.
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