Establishment of the predator Laricobius nigrinus, introduced as a biological control agent for hemlock woolly adelgid in Virginia, USA

Laricobius nigrinus Fender (Coleoptera: Derodontidae), a predatory beetle native to western North America, has been released since 2003 for management of hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae), non-native pest killing hemlocks in eastern America. Over 420,000 L. have the USA from field and lab-reared sources, 14,000 which were deployed Commonwealth Virginia, USA. In order determine establishment rates surveys conducted 2017 2018 at all release sites within this state. During study, stand-level HWA densities estimated, tree health predator–prey ratios quantified. The identification spp. recoveries made using microsatellite analysis. period found established 82% Virginia primary species recovered (80%). Both rubidus (18%) hybrids (2%) also recovered. Stand-level varied greatly over years but showed general decline year two study. Establishment such high percentage suggests that climate is suitable predator insect adaptable wide variety site conditions where typically grow.