[en] The sterility effects were examined on the P1 generation of the black cutworm; Agrotis ipsilon (Hufn.) after gamma sterilization with at 0, 75, 100,125, 150,175 and 200 Gy, to identify the dose of gamma irradiation that would allow for maximum production of partially sterile P1 adults while inducing full sterility in the F1 generation. The studied effects were included the percentage mated males with untreated females, copulation duration to format spermatophores directly in the female bursa copulatrix, number of eggs /female deposited by females mated to irradiated males and egg hatch through three sequential females.The irradiated males with tested doses as well as untreated control were tested for mating successive and starting copulation at the same period of the scotophase. The mating competitiveness calculated from the direct observation in A. ipsilon males emerged from pupae irradiated at doses 75 to 200 Gy was noticed. The effect of substerilizing dose (125Gy) on certain biological aspects and reproduction was studied among parental generation, as well as immature stages were investigated throughout two successive generations. The influence of two entomopathogenic nematodes, Steinernema carpocapsae and Steinernema riobrivae on the insect management was included. Special attention was given to combined effect of F1 progeny of partially sterile males and S. Carpocapsae (All) on A .ipsilon, the combination of tested treatments at all concentrations analyzed for synergistic effect. The parasitisation efficacy of EPNs, the morbidity and mortality induced by normal IJs (i.e., IJs derived from untreated host) and the incubation time taken by normal IJs were compared with these of IJs derived from irradiated host with 125 Gy