Monitoring Azinphosmethyl Resistance in Adult Male Platynota idaeusalis (Lepidoptera: Tortricidae) in Apple from Georgia to New York

Abstract

Sex pheromone traps coated with concentrations of azinphosmethyl-impregnated adhesive were used to test levels of resistance in adult populations of male tufted apple bud moth, Platynota idaeusalis (Walker) from apple orchards in seven Eastern states. Resistance levels >10-fold were found in insects from five of six Adams County, Pa., orchards, one orchard in New Jersey, and one of two orchards in West Virginia. Moderate levels of resistance (5 to 9-fold) were found in insects from the remaining orchard in Adams County, one orchard in New York, and one of two orchards in North Carolina. Males from three Pennsylvania orchards outside of Adams County, the other orchards in West Virginia and North Carolina, one orchard in Georgia, and two orchards in Delaware had low levels of resistance (<4-fold). These results suggest that the level of resistance found within an orchard may be influenced by the intensity of fruit production within a region. Level of resistance to azinphosmethyl was positively correlated with current seasonal carbamate use, but was not significantly correlated with current use of azinphosmethyl or other organophosphates (negative correlation coefficients). Levels of resistance and fruit injury were both significantly correlated with population densities in orchards as measured by mean daily catches of brood I or brood II male moths. Levels of resistance were not significantly correlated with surrounding habitat types or percentage of fruit injury. These results suggest that many apple growers have responded to the development of azinphosmethyl resistance within their orchards with increased use of carbamates and decreased use of azinphosmethyl. Levels of fruit injury were highest in orchards where populations of P. idaeusalis were moderately resistant to azinphosmethyl, seasonal azinphosmethyl use was high, and only small amounts of carbamate insecticides were used.