PARATHION RESISTANCE AND ESTERASE-ACTIVITY IN CODLING MOTH (LEPIDOPTERA, TORTRICIDAE) FROM NORTH-CAROLINA

In 1989, we performed a sticky-card bioassay on adult males captured with pheromone traps that revealed an 8-fold resistance to parathion in a population of codling moth, Cydia pomonella (L.), from a commercial apple orchard in Wilkes County, NC. In 1991, parathion resistance in this population was confirmed with a sticky-card bioassay that exposed adult males to a diagnostic concentration of 120 mug (AI) parathion per gram adhesive (the estimated LC95 for adult males from susceptible populations). Reduced nonspecific esterase activity detected in adult males captured in the population resistant to parathion suggests that the mechanism of codling moth resistance to parathion may be a modified esterase with lower specificity for naphthyl acetate substrates. In 1990, the sticky-card bioassay did not detect azinphosmethyl resistance in adult males from a commercial apple orchard in Henderson County, NC, that experienced inadequate codling moth control with azinphosmethyl. In 1991, the sticky-card bioassay with a diagnostic concentration of 110 mug (AI) azinphosmethyl per gram adhesive (the estimated LC95 for adult males from susceptible populations) again failed to detect azinphosmethyl resistance in adult males from this codling moth population.