Traps and Attractants for Monitoring Navel Orangeworm (Lepidoptera: Pyralidae) in the Presence of Mating Disruption.

The use of aerosol mating disruption for management of the navel orangeworm Amyelois transitella (Walker) in California tree nuts has increased markedly. This treatment suppresses pheromone monitoring traps in neighboring orchards as well as in the orchard under treatment. The current study, therefore, addresses the interrelated topics of which attractant is most effective, how the number of adults captured is affected by trap design, and what sex is captured. Under most circumstances, wing traps baited with phenyl propionate (PPO) captured more adults than those baited with a 5-compound kairomone blend. Adding a pheromone lure along with the dispenser for the experimental attractant increased the number of adults captured with PPO both in and near-mating disruption. In contrast, addition of a pheromone lure along with the kairomone blend only increased the number of adults captured in orchards near but not under mating disruption. Delta traps, which are preferred by the industry, captured fewer adults than wing traps. Improvements in the number of adults captured with PPO in delta traps from addition of a pheromone lure and from design modifications were additive. Both sexes were captured by all attractants and trap designs tested, and the sex ratio was highly variable. Open traps like the wing trap captured a slightly higher proportion of males than closed traps. These findings are discussed in the context of management of the navel orangeworm.