Optimization of Co60 gamma radiation dose for applying sterile insect technique and inherited sterility on Tuta absoluta (Meyrick) in Iran

The objective of this research is to stablish standardized sterile and sub-sterile doses of Co ⁶⁰ gamma radiation on Tuta absoluta (Meyrick) to facilitate the implementation of sterile insect technique for management of this invasive pest of tomato and solanaceous plants. Insects were reared on an artificial diet and pupae were irradiated at 50, 100, 150, 250 and 300 Gy. The fecundity and fertility of untreated females paired with irradiated males, and treated females mated with untreated or treated males, significantly diminished with increasing gamma doses. When pupae were exposed to irradiation at 250 and 300 Gy, completely sterile females and males were obtained, respectively. The adult’s emergence and longevity, were not significantly influenced by irradiation. To perform inherited sterility, male pupae were irradiated by 250 Gy. The F ₁ sex ratio shifted in favor of males. The F ₁ fecundity was diminished compared to the control, and the eggs produced were more sterile. Ultimately, the mating competitiveness of irradiated males by 250 Gy against normal males was assessed at different ratios. Based on the calculated competitiveness value, the release ratio was determined 1:1:1 (irradiated males: unirradiated males: unirradiated females), in which males subjected to irradiation are capable of competing with unirradiated males.