Relative impact of strain, irradiation, and handling on flight performance of navel orangeworm (Lepidoptera: Pyralidae)

Navel orangeworm (NOW) Amyelois transitella (Walker) (Lepidoptera: Pyralidae) is a key pest of almonds, pistachios and walnuts in California. Recently, studies have been initiated to explore the use of gamma irradiated NOW and sterile insect technique (SIT) as an additional control tool for NOW. Previous studies show NOW to be a strong flyer in a laboratory environment, but flight performance of irradiated NOW was unknown until this study. Here, we measured NOW’s flight performance with computerized flight mills and a wind tunnel. Locally reared moths were flown with moths shipped from the Phoenix, AZ USDA APHIS facility. Shipped moths included both irradiated and non-irradiated treatments. On flight mills, moths were flown for a single night recording distance, duration, and velocity. Locally reared moths performed similarly, flying a mean 9.7-11.0 km per night. Shipped moths flew shorter mean distances of 4.6-6.1 km with irradiation showing no compounding effect on performance. In the wind tunnel male NOW were flown in the last 1-2 hours of the scotophase to a female NOW gland extract. Four behaviors were monitored in the tunnel: 1) Wing fanning 2) Initial flight 3) Locking onto plume 4) Source Contact. No significant difference between treatments and controls were found in any of the behaviors measured. The mean percentage of NOW making source contact was 0.63. Findings from this study provide new information on the effects of strain, irradiation, and handling on NOW flight capacity, which is critical to the development of an effective SIT program for this pest.