EFFECT OF OVIPOSITION DAY ON INCIDENCE OF AGONADAL PROGENY OF HELIOTHIS ZEA INFECTED WITH A VIRUS

Authors: Hamm, John; Carpenter, James; STYER, ELOISE - UNIV OF GA VET DIAG LB

Submitted to: Entomology Society Of America Annals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: When a laboratory colony of corn earworm was found to produce a variable percentage of sterile moths, a study was conducted to describe the condition and to determine the cause of the abnormality. The reproductive tracts of both male and female moths were greatly deformed. Some of the female moths contained no ovaries and some of the male moths contained either no testes or greatly reduced and deformed testes. A rod-shaped virus was found associated with the sterile condition. The virus replicated only in parts of the reproductive tract and was produced in especially large amounts in sterile females. Some normal moths also contained a small amount of the virus. These normal moths, which carried the virus, could produce both normal and sterile progeny. Sterile progeny could be produced both by females that carried the virus and by normal females mated to males that carried the virus. It was determined that eggs laid on the first two days of oviposition produced mostly normal moths, whereas, eggs laid on later days produced mostly sterile moths. This explained how the colony could produce a variable rate of sterile moths without all of the moths becoming sterile, thereby losing the colony. Because the larvae feed and developed normally, the virus appears to have little or no potential for use in insect control.

Technical Abstract: An agonadal condition of moths in a laboratory colony of Helicoverpa zea (Boddie) was studied. This condition was associated with nonoccluded baculovirus-like particles which replicated in parts of the abnormal reproductive tracts of agonadal moths and some apparently normal, i.e., fertile, moths. Agonadal female moths exhibited a waxy plug protruding from the vulva. This plug consisted of almost pure virus-like particles within vesicles. The incidence of agonadal progeny in a colony increases with oviposition d from 5.4% for d 1 and 17% for d 2 to 62.8% for d 3. Using an aqueous suspension of material from the waxy plug as inoculum to inject 3- and 4-d-old larvae and to surface-treat eggs, the agonadal condition was produced in moths from a colony of H. zea which had never exhibited the condition. The agonadal condition was produced in progeny of moths that fed on a suspension of virus-like particles, and there was an increase in the incidence of agonadal progeny with progressive oviposition d of infected female parents. An increase in the incidence of agonadal progeny with progressive oviposition d also occurred in progeny of female moths from a noninfected colony mated to males from the infected colony.