Female Indianmeal moths, Plodia interpunctella, respond to synthetic pheromone by altering their behavior

Abstract: Indianmeal moth, Plodia interpunctella, infest a variety of stored products and are
common in many parts of the world. Adult females produce a pheromone that is attractive to
males, encouraging mates to find one another. Mating disruption is a relatively new tactic that uses a synthetically derived pheromone to delay or prevent mating and has shown success in the field. Modelling efforts aimed at understanding the mechanisms behind mating disruption have often focused on the response of the male and the amount of pheromone required to distract or habituate the male away from a calling female. In some other moths, the effect of increased pheromone in the environment leads to significant changes in calling behavior, but the effects of pheromone on female Indianmeal moths is not known. Here we assess a suite of behaviors of female Indianmeal moths when exposed to pheromone. We use two strains collected two years apart and find that the older strain decreases calling when exposed to pheromone lures but the newer strain increases calling behavior when exposed to pheromone lures. Overall movement behavior decreases when females are exposed to pheromone lures. These results suggest that female Indianmeal moths are autodetecting the pheromone lure in the system and are altering their behavior in response. An increase in calling behavior suggests that the female may be trying to compete for accessing to mates, while a decrease in behavior may suggest a relaxing of selection pressures associated with competition for mates. An overall decrease in behavior could be beneficial for the success of mating disruption, as females are restricting themselves from running into a mate simply by chance movements. Further research on the underyling causes of these differences in calling behavior may provide information on genetic differences among these strains or changes in sensory responses induced by laboratory rearing.