Effects of Gamma Radiation on the Tobacco Budworm. I. Irradiation of Pupae

Abstract

Effects of gamma irradiation on pupae of Heliothis virescens (F.) were investigated in the laboratory using a cobalt∞source. None of the eggs oviposited by females from 8- to 10-day-old pupae exposed to 30 krad hatched. There was a 96% decrease in egg viability of females mated to males from 8- to 10-day-old pupae exposed to 40 krad. Egg viability decreased 94.8% in crosses when both males and females as 8- to 10-day-old pupae were irradiated with 15 krad. Males irradiated as pupae were not sexually competitive with normal males. Gamma irradiation at sterilizing dosages appeared to reduce mating frequency and longevity of males as well as longevity and oviposition of females. Considerable mortality was observed in larvae and pupae resulting from fertile eggs from a cross where either of the parents was irradiated as pupae. Resistance to the effects of gamma irradiation increased with pupal age. The LD50 values for 1- to 3-day-old mixed sex pupae, 8- to 10-day-old male pupae, and 8- to 10-day-old female pupae were 6.3, 46.6, and 53.0 krad, respectively.