Biological Control of Emerald Ash Borer in the Southern U.S.: Seasonality, Phenological Synchrony, and Implications for Management

The emerald ash borer (EAB), Agrilus planipennis Fairmare (Coleoptera: Buprestidae), is an invasive wood-boring beetle from Asia. Believed to have been introduced on wooden packaging materials in the early 1990s it was first discovered in the United States in 2002. Since this initial discovery it has spread to 32 states as well as two Canadian provinces. The primary host of EAB is ash trees (Fraxinus spp.), in which EAB can cause mortality in as little as four years. To mitigate the spread and impact of this invasive pest, management plans incorporating the use of conventional pesticides and biological control agents were developed. Of these biological control agents, three larval parasitoids native to the same area as EAB were chosen: Spathius agrili Yang (Hymenoptera: Braconidae), Spathius galinae Belokobylskij and Strazanac (Hymenoptera: Braconidae), and Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae). Along with these introduced parasitoids, several native parasitoids have been evaluated as potential biological control agents of EAB in the United States.A two-year research project to enhance our knowledge of natural enemies of EAB and to assess introduced parasitoids of EAB in the southern United States was initiated. The primary research goals of this project were to: 1) assess establishment of introduced parasitoids and incidence of potential native parasitoids of EAB, 2) determine seasonality and phenological synchrony of EAB and its introduced parasitoids in a southern climate, and 3) assess native parasitoids of EAB and their potential for rearing and release.The results of this research will provide essential knowledge on the current status of introduced parasitoids of EAB in the south as well as insights into the native parasitoids of EAB. This information will inform executive decisions on the management of EAB as a whole and will help to guide future biological control efforts.