Susceptibility of Helicoverpa armigera (Lepidoptera: Noctuidae) to new chemistries in Pakistan

Toxicities of new chemistries viz. fipronil, chlorfenapyr, indoxacarb, spinosad, abamectin and emamectin benzoate, having novel modes of action, were evaluated using an IRAC leaf-dip method against Pakistani field populations of Helicoverpa armigera, which were highly resistant to conventional chemistries. Whereas the majority of populations exhibited susceptibility close to the baselines, there were, nevertheless, signs of resistance development to the new chemistries as demonstrated by a low level of tolerance in many populations. This may be due to a cross-resistance from the resistance mechanisms, particularly metabolic, already selected against older chemistries. If used judiciously and in rotation, the new chemistries can restore the profitability of crop production by counteracting and preventing insecticide resistance in IT armigera and other pests in the future. (C) 2003 Elsevier Science Ltd. All rights reserved.