Codling moth, Cydia pomonella (L.), is the key insect pest of walnuts. Codling moth has developed a moderate to high level of resistance to azinphos-methyl in California walnut orchards. There is a positive correlation between azinphos-methyl resistance and phosmet and esfenvalerate while there is a negative correlation between azinphos-methyl resistance and chlorpyrifos and microencapsulated methyl parathion. The field longevity of azinphos-methyl, phosmet, microencapsulated methyl parathion and esfenvalerate is between two to four weeks while chlorpyrifos is effective for one week. Since chlorpyrifos and microencapsulated methyl parathion provide acceptable codling moth control and since they are negatively correlated with azinphos-methyl resistant codling moth, a resistance management strategy has been constructed using chlorpyrifos and microencapsulated methyl parathion as substitutes for insecticides that show positive correlation with azinphos-methyl resistant codling moth. This resistance management strategy was evaluated in a number of orchards. It appears that azinphos-methyl resistant codling moth populations were reverted to azinphos-methyl susceptible populations by microencapsulated methyl parathion and/or chlorpyrifos applications. However, in orchards using chlorpyrifos and microencapsulated methyl parathion, the codling moth populations were extremely low and it was not possible in all cases to evaluate the degree of susceptibility in the population. In these reverted orchards, it should be possible to stabilize the resistance with occasional microencapsulated methyl parathion or chlorpyrifos applications and transition into a more ecologically sound and stable pest management system using reduced risk insecticides (diflubenzuron, pyriproxifen and tebufenozide) and codling moth pheromone mating disruption.
Species 1: Lepidoptera Torticidae Cydia pomonella (codling moth)
Keywords: Resistance Management, Pesticides
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA