Performance of sterile navel orangeworm using x-ray and electron beam irradiation

Navel orangeworm (NOW) is the most destructive pests of California tree nuts, which account for an annual value of over $6 billion, and 16% of the total agricultural value generated in the state. Recently, the pistachio and almond industries invested in the development of sterile insect technique (SIT) for NOW. Gamma radiation sources have been the primary form of ionizing radiation for SIT in the past, but the development of alternative forms of irradiation, in particular x-ray and electron beam (eBeam) are gaining interest for their safety and reduced regulations. This work focused on assessing the effects of x-ray and eBeam irradiation on the survival, flight ability, and reproductive output of NOW. Moths were exposed to either 0 Gy (control) or 400 Gy (sterilizing dose) using either an X-ray irradiator or eBeam machine to determine dose response on flight capability, longevity and induced sterility. After radiation exposure, 10 males and 10 females from each treatment dose were assessed separately for flight ability across 48 h by placing them in flight cylinders where moths had to fly to successfully escape. Longevity of moths was also assessed daily. Male and female sterility was determined by using single pairs of radiation treated moths paired with a non-irradiated virgin moth of the opposite sex. Eggs were collected daily and allowed to develop. Total eggs, percent hatch, and mature larvae were counted to assess residual fertility of irradiated moths.