Modeling the Impact of a Sex Pheromone/Kairomone Attracticide for Management of Codling Moth (Cydia pomonella)

The pear-derived volatile, ethyl (2E, 4Z)-2,4-decadienoate is a potent, stable, and selective bisexual kairomone for codling moth, Cydia pomonella L. Its discovery creates an unique opportunity to develop monitoring and control tactics targeted for both male and female moths. Here we present a population model that compares the relative effectiveness of a male-only versus a bisexual attracticide. The model tracks daily changes in the population densities of pupae, males, and mated and virgin females using daily survival rates, and natural and insecticide-related mortality for eggs and larvae. The use of sex pheromones for mating disruption is included as a scalar variable affecting mating success. Mating is also influenced by the level of competition between virgin females and the insecticide-laced pheromone point sources (determined by their density and potency). The attractiveness of the kairomone lure is determined by the density and relative attractiveness of individual fruits within the cropping system. The potency (attractiveness and lethality) of the attracticide point sources decline at a constant rate over time. Our modelling results demonstrate that the use of a female attractant greatly improves the effectiveness of the “attract and kill” technique. Our model output is compared with field data collected from apple plots treated with mating disruption and a grid of pheromone/kairomone-baited insecticide-treated stations during 2001. The influence of the seasonal attractiveness of ethyl (2E, 4Z)-2,4-decadienoate for codling moth within walnut, pear, and apple orchard the success of the “attract and kill” approach is discussed. INTRODUCTION Management of codling moth, Cydia pomonella L. with its sex pheromone, codlemone, has been successfully adopted in the western United States and parts of Europe (Thomson et al., 1999). The most widely used approach to date has been the application of 500 – 1,000 plastic dispensers per hectare to disorient moth sexual communication. An alternative behavioural approach for managing codling moth has been the development of pheromone paste formulations containing an insecticidal agent (Charmillot et al., 2000; Lösel et al., 2000). This “attract and kill” approach has been successful in orchards where communication disruption is difficult to achieve due to small orchard size, uneven topography, or high moth immigration (Charmillot et al. 2000). Potting et al. (2000) built a simulation model to study the factors affecting the efficacy of a pheromone-based attracticide for codling moth. This model considered the competition between virgin females and pheromone point sources in luring male moths. Both the potency of the drops and their residual characteristics were important factors affecting the success of this approach. Their model showed that the insecticide-laced pheromone droplets needed to be applied at a density 3 to 5-fold higher than the female moth density. These data suggest that pest species such as codling moth that occur at low population densities, are especially amenable to control with “attract and kill” approaches. However, the propensity of codling moth males to mate with more than a single female Proc. 6th IS on Modelling in Fruit