Insecticide Efficacy Against Trimen’s False Tiger Moth, Agoma trimenii (Lepidoptera: Agaristidae)

Abstract

Trimen’s false tiger moth, Agoma trimenii (Lepidoptera: Agaristidae), has developed pest status in vineyardsin the Northern Cape and Groblersdal areas of South Africa, and an integrated pest management system isrequired. The objective of this study was to test the susceptibility of A. trimenii larvae to three commercialproducts (Delegate®WG, Steward®150 EC and three doses of DiPel® DF). Bioassay tests using all threeproducts, and semi-field trials to test the potential of DiPel® DF against A. trimenii larvae, applied at differentwater volumes (50 g/1 000 L/ha and 50 g/1 430 L/ha) were performed. The residual activity of DiPel® DF,when applied at different water volumes, was investigated daily. Delegate® WG, Steward®150 EC and therecommended dose of DiPel® DF showed 100% larval mortality within seven days. Delegate® WG and therecommended dose of DiPel® DF proved to be the fastest acting products. The product label recommendeddose of DiPel® DF (0.25 g/500 mL distilled water) proved the most effective dose (in comparison to halvedand doubled dosages) and showed 100% mortality five days after application. Increasing the water volumeper ha of a spray application of DiPel® DF for the same application area, showed no significant increasein larval mortality. A reduction in insecticidal activity for DiPel® DF applied at both water volumes wasseen between leaves picked four days after spraying and leaves picked five days after spraying, and nomortality was observed after day 6. To help improve efficacy, attention should be given to increasing spraycoverage and residual activity of DiPel® DF, as well as using all tested products within an integrated pestmanagement system.