Pyrethroid resistance in the pod borer, Helicoverpa armigera

changes in the LD 50 of Helicoverpa armigera to cypermethrin at the International Crops Research Institute for the semi­ Arid Tropics (ICRISAT) and in the coastal cotton-growing region of Andhra pradesh state during the period 1986-92 are summarised and discussed. A provisional discriminating dose of lug cypermethrin was evaluated at ICRISAT and changes in resistance to cypermethrin monitored throughout 1991/92. Resistance was related to seasonal changes in insecticide use; it was lowest in August and increased with progression of the season. Prospects for insecticide resistance management of H. armigera in Andhra Pradesh are briefly discussed