Overwintering Ability of Spathius agrili in Tennessee

Since its initial discovery near Detroit, Michigan, in 2002, the emerald ash borer (EAB), Agrilus planipennis, has caused the death of millions of ash trees. This invasive wood-boring beetle from Asia poses a continuous threat to ash resources in the U.S. In 2010, EAB was first detected in Tennessee. Because ash species comprise about 4% of the hardwood resources in Tennessee forests, EAB has the potential to drastically change forest systems. Because current management options are limited, biological control is the most feasible long-term management option. A larval ectoparasitoid of EAB from Asia, Spathius agrili, has been released extensively in the north-central U.S. These parasitoids have been released in Tennessee beginning in 2012 as part of a biological control program against EAB. Therefore, a study was initiated in 2012 to document the ability of S. agrili to overwinter and establish in the southeastern U.S. In August 2014, more than 40 adult S. agrili were recovered from ash trees contained in whole-tree cages one year following their release. These recoveries demonstrate the ability of S. agrili to overwinter and indicate that they may be able to establish in the southeastern U.S.