Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2019
Publication Date: 1/22/2020
Citation: Burks, C.S., Higbee, B.S., Beck, J.J. 2020. Traps and attractants for monitoring navel orangeworm (Lepidoptera: Pyralidae) in the presence of mating disruption. Journal of Economic Entomology. 113(3):1270-1278. https://doi.org/10.1093/jee/toz363.
Interpretive Summary: The navel orangeworm is a key economic pest moth in California walnuts and pistachios, which are planted on 1.63 million acres and have an annual unprocessed value of approximately $8.2 billion. The rapid growth of navel orangeworm mating disruption, now used on 40% of California almonds and pistachios, completely masks the pheromone traps used for monitoring this pest and necessitates development of other monitoring methods. A three-year study found that one candidate attractant, phenyl propionate (PPO), detected navel orangeworm more robustly in mating disrupted and non-disrupted orchards when compared to a second candidate attractant (a specific and patented blend of almond volatiles referred to as “kairomone blend”). Trap design profoundly affected the performance of PPO; wing traps worked better than the more-popular delta traps, but the delta trap performance could be improved with modifications. While an attractant for capturing principally females would be desirable, both PPO and kairomone blend capture both sexes in widely varying ratios, and usually more males than females are captured. The Almond Board of California and the California Pistachio Research Board have followed this research closely, and two different manufacturers have recently introduced commercial offerings of a PPO lure.
Technical Abstract: Field trials compared the performance of two attractants for monitoring navel orangeworm Amyelois transitella (Walker) (Lepidoptera: Pyralidae) in almond and pistachio in and near mating disruption. When presented by itself in wing traps, phenyl propionate (PPO) captured more navel orangeworm adults than kairomone in sites treated with mating disruption, and non-disrupted orchard in the vicinity of mating disruption. Addition of a pheromone lure significantly increased the number of adults captured with PPO in wing traps in both mating disrupted and non-disrupted sites, whereas for kairomone this effect was observed only in non-disrupted sites. In wing traps, PPO along with a pheromone lure captured more adults than other attractant combinations tested. When presented in delta traps, PPO with a pheromone lure captured no more adults than PPO alone. When openings were cut into the sides of delta traps, improved capture with a pheromone co-attractant was partially restored. The sex ratio was variable and generally male-biased. There was no difference in sex ratio due to mating disruption status, crop, or attractant, but there more males captured in non-disrupted almonds early in the year. Also, closed-sided traps such as delta or bucket traps were slightly less male-biased than wing traps. This characterization of the performance and relative advantages and disadvantages of these attractants and trap types will help the almond and pistachio industries come to consensus on best practices for monitoring the navel orangeworm in the presence of mating disruption.