An interactive model to predict codling moth development and insecticide application effectiveness

Abstract: Following the ban on most organophosphate insecticides, many new products were registered to control the codling moth, Cydia pomonella (L.). Most of these affect specific life stages and have a limited residual activity, so the application timing becomes critical for adequate control. In order to help growers to synchronize insecticide applications with codling moth life stages, we developed an interactive model that predicts the timing of oviposition and hatching of this apple pest. Based on historical adult catches, we predicted female flight, egg laying and larval development from the current knowledge of the biology of codling moth. To test the accuracy of this model, predictions were compared with field observations in two different ways. First, we examined the evolution of the age structure of codling moth larvae and adults under semi-natural conditions. Male emergence, egg laying and hatching were highly correlated to model predictions under these semi-natural conditions. Second, we sampled codling moth adults and larvae from four apple orchards located in different areas. Age of larvae was determined from body length and head capsule width. Approximate date of hatching was back-calculated from temperature records and degree day requirements for larval development. In most cases, the model accurately predicted adult flight from trap catches (r2 > 0.95), egg laying (r2 > 0.97) and hatching (r2 > 0.95). The model was implemented through an interactive platform that enables the user to visualize the impact of a specific insecticide treatment sprayed on a given day on codling moth populations.