Effect of gamma radiation on the male sterility and other quality parameters of peach fruit fly, Bactrocera zonata (Saunders) (Diptera: Tephritidae)

Bactrocera zonata, a serious pest of fruits in many parts of the world, has recently been recorded in Northern Africa. Even though it has not been introduced to the European continent yet, a strong emphasis is being placed on developing effective measures to suppress this pest and to prevent it from establishing in neighbouring European countries. The sterile insect technique is widely used in integrated programmes against tephritid fruit flies and, in this paper, quality parameters of irradiated B. zonata were evaluated for possible use of sterile insect technique within the management of this pest. Pupae were irradiated (60Co) 48 h before adult emergence (in an air atmosphere) with doses of 10, 30, 50, 70 or 90 Gy. While adult emergence and egg hatch decreased with increasing dose, no significant differences in female fecundity were found among doses. Exposure of pupae to 90 Gy resulted in a total sterility of eggs laid by non-treated females crossed with treated males. Only insignificant difference in the radiation effect on female fecundity was found. Moderate effects on sex ratio and size were recorded, as they decreased gradually by increasing doses. No considerable effect on flying capability was observed, but generally, the percentage of fliers decreased with increasing radiation doses. Fried's competitiveness values of treated males (30 and 70 Gy) suggest that irradiated males compete successfully with non-irradiated ones.