Release and Colonization of Laricobius osakensis (Coleoptera: Derodontidae), a Predator of the Hemlock Woolly Adelgid, Adelges tsugae

Biological control of Adelges tsugae (Hemiptera: Adelgidae; Hemlock Woolly Adelgid [HWA]) is an essential component of a management plan for this non-native pest of Tsuga spp. native to eastern N. America. The predatory beetle Laricobius osakensis Montgomery and Shiyake (Coleoptera: Derodontidae) shows potential as a biological control agent because of its coevolved life-cycle with HWA in its native habitat and its voracious appetite for HWA. In the first releases ever made for this species, adult beetles were introduced at 4 sites in the eastern United States with 2 long-term objectives: (1) suppressing HWA populations, and (2) developing field insectaries for re-distribution of predators in the future. Our immediate objectives were to determine the predator's survival and colonization in eastern Tsuga forests following their introduction. In addition, L. osakensis eggs were set out at the 4 release sites. Results from the first year post-release of adult beetles indicated that reproduction occurred at these sites and that beetles survived the summer aestivation period and emerged the following fall. Second-year data were impacted by high HWA mortality due to periods of extreme low winter temperatures. No beetles have yet been collected from any of the 4 egg-release locations.