The seasonality of two parasitoids ( agrili and Tetrastichus planipennisi) of the , Agrilus planipennis, and a survey for native natural enemies of the Emerald Ash Borer in eastern Tennessee

Nicholas A. Hooie

The emerald ash borer (EAB), Agrilus planipennisi Fairmaire, (Coleoptera: Buprestidae) is an invasive species of bark borer native to eastern Asia whose primary habitat and food source are trees in the genus . EAB is a major pest of all North American Fraxinus species and is responsible for mortality of millions of trees across its current North American range consisting of 23 U.S states and two Canadian providences. After the discovery of EAB in Tennessee in 2010, parasitoid releases were conducted under the national EAB Biological Control Program. A research project was initiated in 2012 to 1) study the seasonality of the gregarious larval ectoparasitoid Spathius agrili Yang and the gregarious larval endoparasitoid Tetrastichus planipennisi Yang in the climate of eastern Tennessee, 2) determine the overwintering ability of the parasitoids in field releases, and 3) survey for potential native natural enemies of EAB. In 2013, a single generation of S. agrili developed from egg to pre-pupae in ca. 22 days before overwintering. Adult individuals from the same generation were found to have successfully overwintered in July 2014. These results elucidate S. agrili seasonality. No T. planipennisi successfully parasitized or overwintered. In 2013, S. agrili were successfully recovered from two field sites for the first time in eastern Tennessee. Therefore, after a single year of multiple releases, the successfully overwintering of the parasitoid populations infer the ability of this species to establish within the region. However, no T. planipennisi were recovered from field release sites. Three native parasitoids, Spathius floridanus Ashmead, an undetermined species of Spathius, and Atanycolus cappaerti Marsh & Strazanac, all known to be associated with EAB, were recovered. These recoveries represent the first documentation of these three species associated with EAB in the southern U.S. These findings will help demonstrate the utility of S. agrili in the southern U.S. as a part of the national EAB Biological Control Program.