Title: OVIPOSITIONAL BEHAVIOR OF NEWLY COLONIZED EARWORM, HELICOVERPA ZEA LEPIDOPTERA: NOCTUIDAE), FEMALES AND EVIDENCE FOR AN OVIPOSITION STIMULATING FACTOR OF MALE ORIGIN
Bali, Geetha - UNIV OF MD, DEPT ENTOMOL
Kingan, Timothy - DEPT BIOL SCI, UNIV MD BC
Lopez, Juan DE Dios
Submitted to: Entomology Society Of America Annals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 5, 1995
Publication Date: N/A
Interpretive Summary: The corn earworm is a serious pest of corn, cotton, and soybeans besides a number of other crops. Most studies to date on behavior and physiology of this species have been conducted on insects reared in captivity for a long time. We compared mating and egg laying behavior of such laboratory insects with newly colonized (NC) females. Unlike laboratory-reared females, the NC females required mating for both egg maturation and egg laying. We also obtained evidence that a male factor, transferred during mating, stimulated egg laying. These results emphasize the need to work with wild or NC insects, particularly in studies of behavior. Possible presence of an oviposition stimulating factor should generate interest among scientists working on reproductive behavior and physiology.
Oviposition behavior of newly colonized (NC) females of the corn earworm, Helicoverpa zea (Hubner), was very different from that of females from a laboratory colony. NC 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 NC females. Extracts of male accessory glands, injected into one-day-old virgin females, stimulated both egg maturation and oviposition. During the observation period, the largest number of eggs was laid on the sixth day after treatment. However, five-day-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 JH analog, to virgin females resulted in an increase in egg maturation but not in oviposition.