Introduced parasitoids of emerald ash borer in Tennessee: Promising or perplexing?

The invasive emerald ash borer (EAB), Agrilus planipennis, is a native to eastern Asia whose primary habitat and food source are ash trees of the genus Fraxinus. The feeding of EAB on ash species native to North America has caused the death of millions of ash trees in the U.S. since it was initially discovered near Detroit, MI, in 2002. Since its initial discovery in Tennessee in 2010, controlled studies and open releases of introduced natural enemies [(Oobius agrili (Hymenoptera: Encyrtidae), Spathius agrili (Hymenoptera: Braconidae), and Tetrastichus planipennisi (Hymenoptera: Eulophidae)] of EAB have been conducted in eastern Tennessee. In studies investigating the overwintering ability of larval EAB parasitoids using large and small cages, S. agrili has demonstrated the ability to survive the winters in the south and emerge the following season. However, no T. planipennisi have been observed to successfully overwinter in these studies. Pan trapping at several open release sites has been initiated, and may show survival of one or both species of parasitoids. Results from pan trapping conducted during 2015 will be presented, and the results of controlled studies and pan trapping and their implications to suppression of EAB in the southeastern U.S. will be discussed.