ENDOSULFAN RESISTANCE IN HELICOVERPA-ARMIGERA (HUBNER) (LEPIDOPTERA, NOCTUIDAE) IN AUSTRALIA

Helicoverpa armigera larvae and adults were collected from New South W ales (NSW) and Queensland from 1974 to 1990 and laboratory cultures we re established. Endosulfan was topically applied to third instar larva e of the first or second laboratory generations of the field collectio ns and to a susceptible laboratory strain. The highest levels of endos ulfan resistance (> 50-fold) were recorded in 1974 following several y ears of endosulfan use in the field. Resistance was not detected from 1977 to 1983 when pyrethroids were substituted for endosulfan in the f ield. Since then, resistance has become widespread with the re-introdu ction of endosulfan use. However, these resistance levels have remaine d generally low with only 5 of the 82 strains tested having resistance factors above 10-fold. The highest level of resistance recorded after 1984 was 23-fold and laboratory selection with endosulfan increased t his to 163-fold. From 1986 to 1990, 15-20% of individuals in populatio ns of H. armigera from unsprayed areas of NSW were endosulfan resistan t. The Helicoverpa insecticide resistance management strategy appears to have limited endosulfan resistance.