Insensitive acetylcholinesterase (AChE) was determined to be basically involved in a EPN-resistant (ER) strain and ER contaminated susceptible (CS) strain of diamondback moth (DBM, Plutella xylostella L.), as estimated by the AChE inhibition assay using DDVP as a inhibitor in nondenaturing electrophoresis gel. ER strain exhibited very high insensitivity revel, high resistance ratio and two point mutations (G227A, A201S) in ace1. CS strain showed intermediate insensitivity level, low resistance ratio and a point mutation (G227A). This finding suggests that the A201S mutation along with reported G227A mutation (Baek et al, 2005) can be main player to develop the organophosphate resistance. Additionally, surveyed seven local population DBMs saturated G227A mutation and A201S mutation mixed in some population. Also A441G mutation was detected in some population, but there was no significant correlation. These results suggest that A201S mutation could be one of the good candidate for molecular diagnosis marker of resistance monitoring.

Insensitive acetylcholinesterase (AChE) was determined to be basically involved in a EPN-resistant (ER) strain of diamondback moth (DBM, Plutella xylostella L.), as estimated by the AChE inhibition assay using DDVP and thiodicarb as inhibitors in nondenaturing electrophoresis gel. AChEs were clearly separated into four different bands (a major band and three minor bands) in susceptible strain (CS) and all bands inhibited by used inhibitors almost same level, however, only two bands (a major band and a minor band) showed in that of ER strain and major band showed higher insensitivity. Moreover, ER strain showed cross resistance against used inhibitors and DDVP highly inhibited esterase in both strains. About 2kb of ace1,2 cloned and point mutations were detected in ER strain.