Resistance to synthetic pyrethroids in the bollworm,Heliothis armigera from Andhra Pradesh,India

Helio this armigera collected in October 1987 from Juzzuru in the coastal cotton growing district of Krishna in Andhra Pradesh (Eastern India) were highly resistant to cypermethrin and fenvalerate and moderately resistant to endosulfan. Prior to this, in 1986, H. armigera in the Hyderabad area were resistant to DDT but not to pyrethroids or endosulfan. By late 1987 these latter populations were highly resistant to pyrethroids and mildly resistant to endosulfan. Concurrently, the resistance to DDT increased. It is suggested that resistant moths from the east coast migrated downwind in a northwesterly direction with the prevailing winds which occur at that time of year. The level of pyrethroid resistance in H. armigera infesting pigeon-pea and chick-pea fields around Hyderabad increased steadily up to March 1988. These results are discussed with special reference to the resistance mechanisms likely to be involved.