Screening the optimal dose of gamma radiation for Tuta absoluta sterility: paving the way for sterile insect technique programs

Tuta absoluta (Meyrick) is a destructive pest of tomato crops. The cryptic nature of larvae often leads to low control efficacy. Sterile insect technique (SIT) has the potential to be an alternative management option for T. absoluta. In this study, the optimal dose for T. absoluta sterility was determined by estimating the effect of gamma radiation on parental generation (F0) and their descendants (first and second generation, F1 and F2). Adult emergence was not affected when T. absoluta pupae were exposed to gamma radiation at doses of 100~400 Gy. However, increasing doses of radiation increased deformed individuals and shortened their longevity. Furthermore, as the dose increased, F0 females showed decreased fecundity and fertility, and they were completely sterile when exposed to 300 Gy. The survival and sex ratio of females declined significantly in F1 of irradiated males with increasing doses. Moreover, we found that 300 Gy of gamma radiation did not affect the mating competitiveness of F0 males. Interestingly, this treatment caused a considerable reduction in the number of descendants and caused inherited sterility in F1 by lowering their fecundity and fertility. Therefore, the optimal radiation dose was 300 Gy, and the release of sterile adults may suppress T. absoluta population growth in the field. Our findings provide basis for controlling T. absoluta through SIT programs.