Helicoverpa zea; Heliothis virescens; PATHOLOGICAL-TECHNIQUES; Immunological detection of parasitism by hymenopteran parasites; HYMENOPTERAN-PARASITES; Cotesia marginiventris & Microplitis croceipes; Immunological detection of parasitism Cotesia marginiventris; Microplitis croceipes; PATHOLOGICAL-TECHNIQUES; Immunological detection in lepidopteran host; LEPIDOPTERAN-HOSTS; Helicoverpa virescens & H. zea; Immunological detection of parasitism We have developed a monoclonal antibody that recognizes the larval and adult stages of Microplitis croceipes (Cresson) (Hymenoptera: Braconidae) and Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae), two principal endoparasitoids of the polyphagous pests Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) and Heliothis virescens (F.) (Lepidoptera: Noctuidae). The antibody has been incorporated into an indirect enzyme-linked immunosorbent assay that can be used to distinguish parasitized from unparasitized pests. The antibody cross-reacts with several different hymenopteran parasitoids, but not with any of the noctuid pests we have assayed. An immunoassay based on a broadly reactive antibody such as this one enables comprehensive detection of hymenopteran parasitism with a single antibody reagent. none