AbstractIn 1983, at the onset of pyrethroid resistance in AustralianHelicoverpa 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‐Kdrnerve insensitivity appeared to be a major cause of pyrethroid resistance and contributed to high‐order resistance (>100‐fold). From 1987 to 1990, to monitor the effect of the AustralianHelicoverpainsecticide resistance management strategy on insecticide resistance, we conducted a survey of the frequencies of these mechanisms in field‐collectedH. armigera. The relative importance of thePenandPbomechanisms in resistantH. armigerahave increased butPenandPboconfer only low order (∼ 20‐fold) resistance. We found no evidence of the 1983Super‐Kdrmechanism in the latest samples, but, instead, found another distinctKdr‐type mechanism. This mechanism was correlated with very low‐order nerve insensitivity and was of little toxicological significance. The impact of theHelicoverpainsecticide resistance management strategy on pyrethroid resistance inH. a
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