Maternally induced host regulation by the egg parasitoid Telenomus heliothidis

ABSTRACT. The egg parasitoid Telenomus heliothidis Ashmead (Hymenoptera: Scelionidae) arrested development and prevented emergence of its host, the egg of Heliothis virescens F. (Lepidoptera: Noctuidae). Arrestment was due to a factor injected by the ovipositing parasitoid just prior to egg release. T. heliothidis prevented hatching of H. virescens eggs up to 62 h old. Implantation of the distal region of the parasitoid common oviduct also prevented host emergence. Examination of the distal common oviduct revealed large numbers of protein-containing vesicles in the cytoplasm of the oviduct epithelial cells. These vesicles may be the source of the arrestment factor. The arrestment factor did not prevent emergence of Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae), an interspecific competitor of T. heliothidis.