none Animals and man; Control; Nutrition; Diet; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Land and freshwater zones; Palaearctic region; China Helicoverpa armigera (Noctuidae); Biological control; Food plants; Cotton; Hymenopteran parasites; Campoletis chlorideae & Trichogramma confusum; Prevalence rates, effects of Bt transgenic cotton; Jiangsu; Yangzhou; Bt transgenic crop effects on hymenopteran parasite prevalence rates Campoletis chlorideae (Ichneumonidae ); Trichogramma confusum (Trichogrammatidae ); Lepidopteran hosts; Helicoverpa armigera; Prevalence rates in hosts on cotton, effects of Bt toxin transgenic crops; Jiangsu; Yangzhou; Prevalence rates in lepidopteran hosts on cotton, effects of Bt transgenic crops