Effect of Gamma Radiation on the Sterility and Quality of Male Peach Fruit Fly, Bactrocera zonata (Saunders) (Diptera: Tephritidae)

The sterile insect technique is widely used in integrated programs against tephritid fruit flies. The peach fruit fly, Bactrocera zonata (Saunders) is a serious pest of fruits in many parts of the world. The pest species has been recently recorded in Egypt. Referring to its significant yield losses, recorded on a wide range of fruits, a strong emphasis for developing effective measures to suppress/ eradicate the pest population in infested areas was suggested. In the present study, effect of gamma radiation on adults' emergence, female fecundity, pupal size, flight ability, sex ratio, male sterility and male mating competitiveness was studied under laboratory conditions. Pupae were irradiated ((60)Co) 48 hrs before adult emergence (in an air atmosphere) with 10, 30, 50, 70 or 90 Gy. Results indicated that adults' emergence and egg hatching decreased with increasing radiation dose. Exposure of pupae to 90 Gy resulted in a total sterility of eggs laid by non-treated females crossed with treated males. Insignificant difference in the radiation effect on female fecundity was found. Moderate affects on sex ratio and pupal size were recorded, as they decreased gradually by increasing doses. No considerable effect on flying capability of adults, particularly at a lower height of tubes (5 and 10 cm) was observed. Irradiated males with 30 and 70 Gy successfully competed with non-irradiated ones. According to obtained results, taking into consideration a necessity to compromise between male sterility and competitiveness, the more suitable irradiation dose was <= 70 Gy.