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

  • C. Morris Stellenbosch University
  • A.P. Malan Stellenbosch University
  • J.Y. De Waal Corteva Agriscience
  • S.A. Johnson Stellenbosch University

Abstract

Trimen’s false tiger moth, Agoma trimenii (Lepidoptera: Agaristidae), has developed pest status in vineyards
in the Northern Cape and Groblersdal areas of South Africa, and an integrated pest management system is
required. The objective of this study was to test the susceptibility of A. trimenii larvae to three commercial
products (Delegate®WG, Steward®150 EC and three doses of DiPel® DF). Bioassay tests using all three
products, and semi-field trials to test the potential of DiPel® DF against A. trimenii larvae, applied at different
water 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 the
recommended dose of DiPel® DF showed 100% larval mortality within seven days. Delegate® WG and the
recommended dose of DiPel® DF proved to be the fastest acting products. The product label recommended
dose of DiPel® DF (0.25 g/500 mL distilled water) proved the most effective dose (in comparison to halved
and doubled dosages) and showed 100% mortality five days after application. Increasing the water volume
per ha of a spray application of DiPel® DF for the same application area, showed no significant increase
in larval mortality. A reduction in insecticidal activity for DiPel® DF applied at both water volumes was
seen between leaves picked four days after spraying and leaves picked five days after spraying, and no
mortality was observed after day 6. To help improve efficacy, attention should be given to increasing spray
coverage and residual activity of DiPel® DF, as well as using all tested products within an integrated pest
management system.

Author Biographies

C. Morris, Stellenbosch University

Department of Conservation Ecology and Entomology, Faculty of AgriSciences, Stellenbosch University, South Africa.

Department of Microbiology

Distinguished Professor

A.P. Malan, Stellenbosch University

Department of Conservation Ecology and Entomology, Faculty of AgriSciences, Stellenbosch University, South Africa.

J.Y. De Waal, Corteva Agriscience

Corteva Agriscience, Centurion, Gauteng, South Africa

S.A. Johnson, Stellenbosch University

Department of Conservation Ecology and Entomology, Faculty of AgriSciences, Stellenbosch University, South Africa.

Published
2022-05-17
Section
Articles