Effectiveness of <i>Beauveria bassiana</i> against <i>Piezodorus guildinii</i> (Hemiptera: Pentatomidae), a key pest of soybeans in the neotropics
Katherine A. Parys, Maribel Portilla
Abstract
Redbanded stink bug, Piezodorus guildinii (Westwood), is a neotropical pest of soybean in the southern United States and the Neotropical Americas. Two strains of Beauveria bassiana (Bals.-Criv) Vuill. (Hypocreales: Cordycipitaceae) were evaluated for potential control of redbanded stink bug. Four concentrations (104, 105, 106, and 107 spores/mL) of both a Mississippi Delta native strain (NI8) and a commercially available formulation (GHA) were tested against field-collected redbanded stink bug adults in the laboratory and evaluated at four time points (3, 5, 10, and 15 days after application). Application methods simulated field sprays and were similar to those previously used to screen several other pests and beneficial insects. Both isolates of B. bassiana tested were pathogenic to redbanded stink bug adults. A significant overall difference between strains (regardless of the concentration) was observed at 3 days after treatment, while differences among concentrations were observed at 10, and 15 days after treatment. The lethal concentration (LC50) and lethal sporulation (LS50) were not significantly different between strains at either 10 or 15 days after treatment. However, higher mortality was observed in cohorts sprayed with GHA at lower concentrations than those sprayed with NI8. Unlike other control options, B. bassiana has a short re-entry interval and no harvest interval, making it a potentially attractive and environmentally benign alternative to conventional synthetic insecticides for control of redbanded stink bug in soybeans. Further testing on juvenile life stages and field testing is needed to evaluate the potential for in-field control.