Gamma Irradiation of Pupae of the Tobacco Budworm1

Publisher Website
Google Scholar
Abstract
Pupae of the tobacco budworm, Heliothis virescen (F.), were irradiated with Cobalt-60 gamma rays about 2 days before adult emergence. Male moths were 99% sterile after a dose of 35 kilorads. Female moths produced very few eggs when the dose was greater than 35 krad, though there was some egg hatch at this dose level. The emergence and lifespan of both sexes were reduced by sterilizing doses. The initiation and length of the oviposition periods for females mated with either treated males or untreated males were similar. However, females crossed with treated males produced significantly fewer eggs. Virgin females laid eggs, but their oviposition began later and was shorter than that of females crossed with males. The average lifetime production of eggs for single pairs of control moths was about 800 eggs, though some females did produce more than 1600. When the sterility data from irradiated males were plotted, the resulting dose-response curve appeared to be sigmoidal. Cytological observations on spermatogenesis indicated that sperm were present in the testes of the pupae at the time of irradiation.