Out of four insecticides evaluated for their relative toxicity to Diaereteilla rapae, a common parasitoid of mustard aphid Lipaphis erysimi (Kalt.), dimethoate, methyldemeton and cypermethrin were found highly toxic (78.33 to 94.94% mortality) to the adult parasitoids under direct exposure. Whereas, phosphamidon was comparatively less toxic (37.7 to 38.8% mortality). Also, male parasitoids were more susceptible to insecticides than females. BR Reproduction. Sex differences. Parasites diseases and disorders. Parasites. Insect parasites. Hosts. Insect hosts. Abiotic factors. Chemical factors. Diaeretiella rapae (Aphidiidae): Parasite; Lipaphis erysimi (Aphidoidea): Host. Diaeretiella rapae: Physiological and biochemical sex differences, Hemipteran hosts, Lipaphis erysimi, Relative non-target susceptibility of parasitoids to insecticides, biocontrol implications, Fertilizers and pesticides, Methyl demeton, dimethoate, phosphamidon and cypermethrin; Lipaphis erysimi: Hymenopteran parasites, Diaeretiella rapae, Relative non-target susceptibility of parasitoids to insecticides, biocontrol implications. ST Insecta, Hymenoptera, Apocrita, Terebrantia, Ichneumonoidea, Aphidiidae; Insecta, Hemiptera, Homoptera, Sternorrhyncha, Aphidoidea. Arthropods; Hymenopterans; Insects; Invertebrates; True Bugs. none