Females codling moths evade the mating disruption control tactic

Abstract Mating disruption, an environmentally friendly pest-control method, utilizes synthetic sex pheromones to interfere with males' ability to locate females for mating. An increase in successful mate encounters can occur due to uneven distribution of synthetic pheromones in the field, allowing males to locate and mate with calling females in areas of low pheromone concentration and areas with larger pest populations, where random encounters between males and females are more likely to happen by chance. The study results demonstrate greater fruit damage and higher abundances of male and female codling moths (Cydia pomonella)in the margins compared to the centers of mating disruption-treated apple orchards. We suggest larger pest populations build up at the orchard margins over the season due to the following behavioral cascade: Females flee areas of high pheromone concentration to reduce the perceived “competition” for mates, while mated females move to the margins to minimize future “competition” for offspring's resources. Males then track the higher female population at the margins by following the females' full pheromone blend. To our knowledge, this is the first study to offer an interpretation supported by empirical data for the puzzling phenomenon of higher fruit damage in field margins under mating disruption.