Use of Feeding Stimulants to Enhance Insect Growth Regulator-Induced Mortality of Fall Armyworm (Lepidoptera: Noctuidae) Larvae

Abstract

The mortality of fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), larvae was significantly increased when they fed on leaves of southern pea Vignaunguiculata [L.] that had been treated with either of two insect growth regulators (IGRs) (RH-5992 and diflubenzuron), in combination with Konsume@^R, a cottonseed flour based insect feeding stimulant. Larval mortality was increased 2 and 3 days after treatment when Konsume (10% solution) and RH-5992 at 0.001 and 0.01% active ingredient [AI] were applied in combination, respectively. Similarly, a 10% solution of Konsume enhanced the effects of diflubenzuron (0.01% AI) on FAW larvae 4, 6, and 7 days after treatment. A 5% solution of Konsume mixed with diflubenzuron (0.001% AI) resulted in significantly greater fall armyworm larval mortality 2-5 days after treatment compared with diflubenzuron alone. The feeding stimulants Nu-Lure@^R, Coax@^R and Konsume all performed similarly against FAW larvae when mixed with either RH-5992 or diflubenzuron. However, Nu-Lure and Coax mixed with the IGRs did not significantly increase fall armyworm mortality above that caused by the IGRs alone. The simultaneous use of a feeding stimulant, such as Konsume, may provide an effective tool to increase toxicant activity of RH-5992 or diflubenzuron, and decrease the time needed to effect death of fall armyworm larvae.