The effect of transgenic double genes, Cry1A+CpTI cotton and Cry1Ac toxin on the parasitoid, Campoletis chlorideae Uchida of cotton bollworm, Helicoverpa armigera (Hubner), was investigated in the laboratory. Helicoverpa armigera larvae when in the first, second and third instar could not survive if fed on transgenic cotton leaves. Consequently, C. chlorideae larvae could not complete their development if parasitizing on such hosts. After H. armigera larvae were reared on transgenic or traditional cotton leaves for 12J48 hours, they were parasitized by C. chlorideae females. Parasitized larvae continued to feed on transgenic or traditional cotton for 1248 h. The present results showed that the body weight of larvae of the parasitoids were significantly reduced when parasitized hosts fed on transgenic cotton leaves compared to those fed on traditional cotton. Duration of egg and larvae stage were significantly prolonged, pupal and adult weight of C. chloridae was decreased when the host larvae fed on transgenic cotton leaves longer than 48 h. The development duration of C. chlorideae pupae on the hosts fed on transgenic cotton leaves in each treatment was not significantly different from those of controls. The longevity of parasitoid females and males fed with a solution containing Cry1Ac toxin was not significantly different with that of the control. Helicoverpa armigera (Noctuidae) : Host Campoletis chlorideae (Ichneumonidae) : Parasite Biometrics; Nutrition; Diet; Life cycle and development; Development; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology; Population dynamics Campoletis chlorideae; Weight; Development; Longevity; Lepidopteran hosts; Transgenic cotton effects on host quality & parasite performance; Helicoverpa armigera Helicoverpa armigera; Food plants; Transgenic cotton; Hymenopteran parasites; Transgenic cotton effects on host quality & parasite performance; Campoletis chlorideae; Survival none