Control of diamondback moth (Lepidoptera: Plutellidae) in Eastern US commercial brassica fields using hand-applied pheromone dispensers for mating disruption

Plutella xylostella (L.) (Lepidoptera: Plutellidae), known as the diamondback moth, is a destructive and challenging pest to manage in brassica crop systems due to its persistence promoted by insecticide resistance. Using synthetic sex pheromone-loaded solid dispensers, we conducted field trials in 2022 and 2023 to assess the efficacy of mating disruption on reducing P. xylostella pest pressure in commercial fields in Virginia, North Carolina, and South Carolina. Crops included in these experiments were cabbage, broccoli, and collards. Participating growers were asked to continue with all commercial practices, including the application of pesticides. Adult captures in sex pheromone-baited monitoring traps served as an indicator of adult P. xylostella mating activity. Immature presence and leaf severity ratings were collected by sampling plants in experimental fields. Trials were conducted during the commercial growing season in each state. We concluded that the use of solid dispensers for mating disruption of P. xylostella provided effective suppression of adult moth reproductive activity in brassica systems. While we did not detect differences in larval density or feeding damage between our untreated control and mating disruption fields, the growers applied a vigorous insecticide program that likely controlled insects in the untreated control plots, thus masking any differences that would have occurred based on the number of moths captured inside the untreated control fields. Our data suggests that mating disruption could be paired with current control practices to reduce the presence of P. xylostella resistant to insecticides sprayed in the Eastern United States.