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 the corn earworm, Helicoverpa zea (Hübner), was very different from that of females from a laboratory colony. Newly colonized virgin females laid very few eggs, and mated females required a host plant or a part of it such as corn silk for egg laying. Mating stimulated both egg maturation and oviposition in newly colonized females. Extracts of male accessory glands injected into 1-d-old virgin females, stimulated both egg maturation and oviposition. During the observation period, largest number of eggs was laid on the 6th d after treatment. However, 5-d-old virgin females injected with the accessory gland extract showed a significant increase in oviposition within 24 h. Further purification of the active factor is in progress. Females mated to males from which testes, accessory glands, and the duplex had been removed behaved like virgins. Topical application of methoprene, a juvenile hormone analog, to virgin females resulted in an increase in egg maturation but not in oviposition.