OVIPOSITIONAL BEHAVIOR OF NEWLY COLONIZED CORN-EARWORM (LEPIDOPTERA, NOCTUIDAE) FEMALES AND EVIDENCE FOR AN OVIPOSITION STIMULATING FACTOR OF MALE ORIGIN

Oviposition behavior of newly colonized females of tile cent earworm, Helicoverpa zea (Hubner), was very differ ent from that of females fro m a laboratory colony. Newly colonized virgin females laid very few eg gs, and mated females required a host plant or a part of it such as co rn silk for egg laying. Mating stimulated both egg maturation and ovip osition in newly colonized females. Extracts of male accessory glands injected into 1-d-old virgin females, stimulated both egg maturation a nd oviposition. During the observation period, largest number of eggs was laid on tile 6th d after treatment. However, 5-d-old virgin female s injected with tile accessory gland esl act showed a significant incr ease in oviposition within 24 h. Further purification of tile active f actor is in progress. Females mated. to males from which testes, acces sory glands, and the duplex had been removed behaved like virgins. Top ical application of methoprene, a juvenile hormone analog, to virgin f emales resulted in an increase in egg maturation but not in ovipositio n.