The Peach fruit fly, Bactrocera zonata (Saunders) is a serious devastating pest in Egypt. This pest spends in soil from full grown larvae till adult emergence. Therefore, the present study was planned to evaluate the pathogenicity of Steinernema scapterisci against larvae and 1 day old pupae (at different soil depths), and to investigate the effect of gamma radiation on its virulence. The results revealed that adult emergence percentage decrease as the soil depth and S. scapterisci concentration increase. In contrast, the larval mortality increased with S. scapterisci concentration increased. In addition, this study showed that gamma irradiation of S. scapterisci juveniles with 2Gy increased its virulence against both larvae and pupae, which presented by lower LC₅₀ values than unirradiated S. scapterisci . Subsequently, it could be concluded that 2Gy irradiated S. scapterisci can serve as a bio-tolerated control method for B. zonata .