Analysis of the Survival and Reproduction of the Codling Moth in Harvested Walnuts

Previous studies supported by the Walnut Board had shown that survival of codling moth (CM) larvae is proportional to their age at the time of harvest and that overall survival is poor compared to siblings reared on artificial diets. In 1986 considerably more data were collected on the infestation levels of codling moth in different varieties of walnuts. In addition, the population structure at the time of harvest ~s clarified. Survival of different CM stages on walnuts under different storage conditions was investigated. Also investigated were the ability of CM to mate under storage conditions, sequences of emergence of the sexes, rates of larval development, influence of temperature on adult fecundity as related to adult age, affect of duration of diapause upon adult emergence, mating, oviposition and longevity and effect of moth density on mating. Studies were also conducted to determine the minimum densities of CM that would allow mating in walnut masses equivalant to a 50 lb. shipping bag. These data will be used to support reduction in the severity or elimination of the present quarantine treatment for Japan.