83Crop Pests and Diseases New Zealand Plant Protection 53:83-86 (2000) IMPORTED INSECTICIDE RESISTANCE IN DIAMONDBACK MOTH

Laboratory experiments were conducted to determine whether resistance in an Australian population of diamondback moth could be conferred to a local susceptible population of diamondback moth (Plutella xylostella). Bioassays with larvae showed a 715-fold difference in response at the LC50 to alpha-cypermethrin between the resistant imported and local susceptible populations. The response of a hybrid strain from these populations displayed a lower level of resistance, and a backcross of hybrids with the parents an even lower level of resistance. The hybrid strain did not suffer any fitness disadvantage when compared with the parents. Keywords:Plutella xylostella, resistance, alpha-cypermethrin, bioassay