Season-long comparison of trap lures for integrated management of the navel orangeworm (Lepidoptera: Pyralidae) in almond and pistachio

Authors: Siegel, Joel; Burks, Charles - Chuck; WILSON, HOUSTON - University Of California, Riverside

Submitted to: CABI Agriculture and Bioscience (CABI A&B)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2024
Publication Date: 3/25/2024
Citation: Siegel, J.P., Burks, C.S., Wilson, H. 2024. Season-long comparison of trap lures for integrated management of the navel orangeworm (Lepidoptera: Pyralidae) in almond and pistachio. CABI Agriculture and Bioscience (CABI A&B). 5. Article 30. https://doi.org/10.1186/s43170-024-00236-z.
DOI: https://doi.org/10.1186/s43170-024-00236-z

Interpretive Summary: Trapping is an important element of orchard pest management for control of the navel orangeworm, the primary insect pest of almond and pistachio in California. Trapping is now more complicated because the widespread use of mating disruption for control of this pest interferes with the pheromone lure used for its monitoring. Other lures are available that are minimally affected by mating disruption, and this study evaluated both a natural bait that is attractive to ovipositing females and a volatile chemical named phenyl propionate (PPO), that is attractive to both sexes and is synergized when combined with pheromone lures. In this paper we refer to the combination of a pheromone lure + a PPO lure as “combo”. We used the season-long trap capture for these two attractants from a sterile insect technique (SIT) demonstration project located in Fresno County, California. 2020-2022. There was a moderate, season-long correlation in female capture between the two lures types and the correlation strengthened when only the data for the period leading up to July 21 (Julian date 202) were used. For Bait lures in almond, 48.7% of the trap catch occurred by July 21, while in pistachio 87.1% of the trap catch occurred by July 21. In almond, 38.9% of the Combo trap catch occurred by July 21 while in pistachio 54.6% of the catch occurred by that date. Bait lures were most effective before July 21, likely due to diminished attractiveness as new crop nuts split in August through October while Combo lures performed similarly season-long.

Technical Abstract: Monitoring the population of the navel orangeworm (Lepidoptera: Pyralidae), the primary insect pest of almond and pistachio in California, is now complicated by the widespread use of mating disruption for its control. Lures that are minimally affected by mating disruption include natural ovipositional substrates (Bait) and phenyl propionate (PPO), a volatile chemical that attracts both sexes and is synergized when combined with pheromone lures (Combo lures). We compared the season-long trap capture for these two attractants in a sterile insect technique (SIT) demonstration project in Fresno County, California. A total of 194,233 males (96.52%) were caught using Combo lures and 7,006 (3.48%) caught using Bait lures, while 95,947 females (48.83%) were caught using Combo lures and 100,532 (51.17%) caught using Bait lures, 2020-2023. Capture of A. transitella was 2.3-fold higher in pistachio (278,492) than in almond (119, 316). There was a moderate, season-long correlation in female capture between the two lures. The correlation strengthened when only the data for the period leading up to July 21 (Julian date 202) were used. For Bait lures in almond, 48.7% of the trap catch occurred by July 21, while in pistachio 87.1% of the trap catch occurred by July 21. In almond, 38.9% of the Combo trap catch occurred by July 21 while in pistachio 54.6% of the catch occurred by that date. Bait lures were most effective before July 21, likely due to diminished attractiveness as new crop nuts split in August through October while Combo lures performed similarly season-long.