Pyrethroid resistance mechanisms in Australian <i>Helicoverpa armigera</i>

Abstract

Abstract In 1983, at the onset of pyrethroid resistance in Australian Helicoverpa armigera , three resistance mechanisms were identified. They were: a strong nerve insensitivity ( Super ‐ Kdr ), penetration resistance ( Pen ), and a factor which was overcome by piperonyl butoxide ( PBO ). Super ‐ Kdr nerve insensitivity appeared to be a major cause of pyrethroid resistance and contributed to high‐order resistance (&gt; 100‐fold). From 1987 to 1990, to monitor the effect of the Australian Helicoverpa insecticide resistance management strategy on insecticide resistance, we conducted a survey of the frequencies of these mechanisms in field‐collected H. armigera . The relative importance of the Pen and Pbo mechanisms in resistant H. armigera have increased but Pen and Pbo confer only low order (∼ 20‐fold) resistance. We found no evidence of the 1983 Super ‐ Kdr mechanism in the latest samples, but, instead, found another distinct Kdr ‐type mechanism. This mechanism was correlated with very low‐order nerve insensitivity and was of little toxicological significance. The impact of the Helicoverpa insecticide resistance management strategy on pyrethroid resistance in H. armigera is discussed.