Evaluating response of mass-reared and irradiated navel orangeworm, Amyelois transitella (Lepidoptera: Pyralidae) to crude female pheromone extract

Authors: REGER, JOSHUA - University Of California; WENGER, JACOB - California State University; BRAR, GURREET - California State University; Burks, Charles - Chuck; WILSON, HOUSTON - University Of California

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/13/2020
Publication Date: 10/15/2020
Citation: Reger, J., Wenger, J., Brar, G., Burks, C.S., Wilson, H. 2020. Evaluating response of mass-reared and irradiated navel orangeworm, Amyelois transitella (Lepidoptera: Pyralidae) to crude female pheromone extract. Insects. 11(10):703. https://doi.org/10.3390/insects11100703.
DOI: https://doi.org/10.3390/insects11100703

Interpretive Summary: The navel orangeworm is an important pest of almonds and pistachios in California, and sterile insect technique (SIT) is being explored as an additional component of management of this pest. Preliminary field releases of sterile navel orangeworm shipped from a facility in Phoenix, AZ resulted in poor recovery of males in pheromone traps, raising concerns about the mass-reared male moths’ quality. In this wind tunnel study the response to female sex pheromone of irradiated and non-irradiated mass-reared navel orangeworm males was compared to two strains of locally reared non-irradiated navel orangeworm. Initial responses were similar for all moths tested, but a lower proportion of mass-reared moths contacted the pheromone source. The underlying mechanism for this reduction remains unclear but is likely related to damage incurred during the mass-rearing and shipping process. These findings are being used to refine methods previously used for the pink bollworm SIT program to meet the needs of the multi-million dollar NOW SIT project.

Technical Abstract: The navel orangeworm, Amyleois transitella (Lepidoptera: Pyralidae) is a key pest of almonds and pistachios in California. Larvae directly feed on nuts, reducing quality and yield, and adults can introduce fungi that produce aflatoxins. The development of sterile insect technique (SIT) is currently being explored as a management tool for this pest. Large quantities of A. transitella are mass-reared, irradiated, and shipped to California from a USDA APHIS facility in Phoenix, AZ. Preliminary field releases of sterile A. transitella from this facility resulted in poor recovery of males in pheromone traps, raising concerns that mass-reared male A. transitella may not be responding to pheromone from virgin females. In this study, a wind tunnel was used to evaluate the response of both irradiated and non-irradiated mass-reared A. transitella males to crude pheromone extract from females, and their performance was compared to two strains of locally reared non-irradiated A. transitella. While initial responses associated with pheromone detection where similar between mass-reared and locally reared moths, a lower proportion of the mass-reared moths ultimately made contact with the pheromone source. Surprisingly, the addition of irradiation did not further decrease their performance. While mass-reared moths respond to pheromone, their ability to locate and make contact with pheromone source appears to be impeded. The underlying mechanism remains unclear but is likely related to damage incurred during the mass-rearing and shipping process.