D3444: Overwintering survivability of Rhinoncomimus latipes (Coleoptera: Curculionidae), a biological control agent of invasive mile-a-minute weed

Successful overwintering of biological control agents is a critical component in achieving sustainable biological control programs. Rhinoncomimus latipes Korotyaev (Coleoptera: Curculionidae) is a biological control agent of mile-a-minute weed (Persicaria perfoliata) that has been released and utilized for several decades in the United States. However, the overwintering success and the location of the overwintering sites of R. latipes are poorly understood. Given the highly host-specific nature of R. latipes, we hypothesized that R. latipes may not disperse far from their host plant during the overwintering period. We conducted two experiments to estimate the overwintering survivability of R. latipes in an area where mile-a-minute weed has been introduced. In the first experiment, we established ten field cages, each containing 30 R. latipes, before the first frost. All field cages were situated under dense mile-a-minute weed thatch. In the second experiment, we compared R. latipes densities under mile-a-minute weed cover with those in areas without mile-a-minute weed in the same site. We retrieved overwintered R. latipes from the field cages and topsoil samples in the subsequent year. The results of this study showed that the overwintering success rates were 14.67% and most R. latipes were overwintered under the mile-a-minute weed cover. Our results can be used to develop conservation biological control strategies by protecting R. latipes overwintering sites.