Parasitoids emerging from trees colonized by native Agrilus in Wisconsin

We examined parasitoids associated with three native Agrilus species, twolined chesnut borer (Agrilus bilineatus), bronze birch borer (Agrilus anxius), and bronze poplar borer (Agrilus liragus), in Wisconsin. Wisconsin is on the western leading edge of the invasive Emerald ash borer (Agrilus planipennis), and has multiple established populations. Research has shown that some native natural enemies can cause mortality to A. planipennis, so our objective was to generate baseline data that could help both gauge this potential and evaluate potential nontarget effects of various control programs. Infested Quercus rubra, Betula papyrifera, and Populus tremuloides were felled during the summers and falls of 2010 and 2011 from various locations throughout Wisconsin. Trees were sectioned into approximately 0.76-0.91 meter lengths, and the ends were waxed to prevent desiccation. Logs were stored at ~4 °C until transferred to rearing containers starting in January 2012 and ending in January 2013. Rearing containers were held at approximately 27 °C. Emerging parasitoids were collected daily for 4 months and identified. After emergence had terminated, the bark was removed, and the presence and size of Agrilus galleries, and parasitism, were quantified. We collected 405 Hymenoptera, of which 60% were reared from Q. rubra, 29% from B. papyrifera, and 11% from P. tremuloides. Wasps comprised 16 families and least 20 genera and 22 species.