First field validation of <i>Ontsira mellipes</i> (Hymenoptera: Braconidae) as a potential biological control agent for <i>Anoplophora glabripennis</i> (Coleoptera: Cerambycidae) in South Carolina

Abstract The Asian longhorned beetle, Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), is an invasive woodboring beetle present in several areas in North America. The typical management strategy for this pest involves eradicating incipient A . glabripennis populations from a detected area by removing all infested and high-risk hosts, and therefore, all beetles. While effective, this method may not work in all areas, particularly those that are perpetually wet or swampy and where access for tree removal is limited. Biological control may be a viable and complimentary management strategy in these areas, as natural enemies act on a landscape scale rather than individual trees. Recently, a native parasitoid, Ontsira mellipes Ashmead (Hymenoptera: Braconidae), was found parasitizing A . glabripennis and shows effective host-finding behavior under controlled conditions. The active A . glabripennis infestation in South Carolina, U.S. provides an opportunity to conduct the first field validation of the ability of O. mellipes to find and use A . glabripennis as a host. Adult O. mellipes were released on several trees infested with A . glabripennis in the South Carolina quarantine zone in summer 2023, and after 3 weeks trees were destructively sampled. Two A . glabripennis larvae were found to be attacked by O. mellipes , a result confirmed by DNA sequencing. This represents the first field validation that laboratory-reared O. mellipes can and will attack and use wild A . glabripennis as hosts. While additional research is needed to identify optimal release timing, and to determine the efficacy of O. mellipes as a biological control agent, these results suggest this strategy may be a useful supplement to the current A . glabripennis management strategy.