Resistance to insecticides has repeatedly developed in Helicoverpa armigera around the world and is of major concern to the cotton industry in Australia.

The suspected importance of pyrethroid metabolism in resistant H.armigera. made the investigation the biochemical basis of pyrethroid resistance in H. armigera imperative.

A complex of pests attacks the Australian cotton crop, none more important than the cotton bollworm, Heliothis armigera. and insecticides are considered necessary for its control. H.

The frequency of resistance to synthetic pyrethroids in Heliothis armigera has been monitored in the Namoi Valley since the introduction of the insecticide resistance management strategy in 1983.

Although resistance to insecticides was a well-documented phenomenon, pest control operators have merely switched from less effective insecticides to newer more potent compounds and thereby kept ahead of the resistanc