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

The tomato leaf miner, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is one the most important pest of solanaceous plants in Iran and worldwide. Given the resistance of this pest to pesticides, it seems necessary to investigate the possibility of controlling this pest using bio-safe control methods such as the sterile insect technique (SIT) and inherited sterility technique (IST) in Iran. For this purpose, larvae were reared on an artificial diet and pupae were irradiated with Co60 gamma irradiation at 100, 150, 200, 250, and 300 Gy. In the parental generation, the adults’ emergence and longevity were not significantly influenced by irradiation. 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 progeny of male parents irradiated with semi-sterile dose (250 Gy) and mated with unirradiated females significantly shifted in favor of males (74%) in the first filial generation (F1). The eggs laid by the F1 male and females were sterile and this sterility was more pronounced in males (100%) than in females (98.57%). Based on the competitiveness value (2.60), males irradiated at 250 Gy (IM) successfully competed against untreated males (UM) for mating with untreated females (UF), even at a 1:1:1 ratio of IM:UM:UF. These results indicate that 250 Gy Co60 gamma ray is appropriate dose in SIT/IST programs against T. absoluta in Iran.