Repellency trials and vial bioassays of spinosad on adult stink bugs

Stink bugs (Hemiptera: Pentatomidae) are currently the major soybean pest in the mid-South. In Louisiana, the redbanded stink bug, Piezodorus guildinii (Westwood), is the dominant stink bug species, comprising 59 to 72% of the total stink bug species found in soybean throughout the growing season. Redbanded stink bug is very tolerant of products available for stink bug control and, consequently, insecticide applications have significantly increased. Currently, only one product labeled for soybean (acephate) maintains redbanded stink bug populations below the action threshold of 6 insects per 25 sweeps for seven days post-treatment. Preliminary research indicates that even when acephate was applied for redbanded stink bug control starting at R4 (full pod), four to six applications were needed to significantly reduce yield loss. Previous research indicated that spinosad has efficacy against Euschistus servus (Say) and Acrosternum hilare (Say), and acts as an attractant to E. servus. The prospect of an attractant and effective insecticide has broad implications as an alternative control strategy for stink bugs in soybean. Thus, laboratory research was undertaken to study the effects of spinosad on other stink bug species. Spinosad in the form of Entrust (Dow AgroSciences, Indianapolis, IN) attracted Oebalus pugnax (F.), but not redbanded stink bug or Nezara viridula (L.). Spinosad in the form of Tracer (Dow AgroSciences, Indianapolis, IN) did not attract or repel. Vial bioassays indicate that N. viridula is more susceptible than redbanded stink bug to spinosad.