PYRETHROID-RESISTANT HELICOVERPA-ZEA AND TRANSGENIC COTTON IN SOUTH-CAROLINA

Failures to control Helicoverpa tea (Boddie) on cotton in South Caroli na were associated with resistance to pyrethroid insecticides. Resista nce to cyhalothrin, cypermethrin, and permethrin was observed in a col ony collected as larvae from cotton in Estill, SC, in September 1996. Cyhalothrin resistance was expressed as an incompletely dominant trait . In 1997, resistance to cyhalothrin was observed in males captured in pheromone traps in Estill and nearby Ulmer. Resistance was also obser ved in Cameron and Holly Hill (Santee), SC, 150 km to the north, in ad ults reared from larvae collected from cotton. In contrast, all moths trapped in the Pee Dee River drainage 300 km to the north were suscept ible. Putative mechanisms for resistance as related to improved monito ring of population genetics and implications for control of pests on t ransgenic insecticidal cotton are discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.