Dominant Lethal Mutations in Insects with Holokinetic Chromosomes: Irradiation of Pink Bollworm1 Sperm3

Abstract

Adult males of the pink bollworm, Pectinophora gossypiella (Saunders) were irradiated with 19 and 30 krad of gamma radiation and mated with virgin, untreated females. Males treated with 19 or 30 krad of gamma radiation, at 2–24-h or 48–72-h postemergence, respectively, did not show reduced mating frequency compared with the untreated male controls. However, transfer of eupyrene sperm was reduced by treating 2–24-h postemergent males with 30 krad. Irradiation with 19 or 30 krad did not cause complete male sterility; 12.7 and 16.8%, respectively, of the fertilized eggs hatched. Eggs fertilized with irradiated sperm were examined cytologically and showed a retardation of embryonic development up to the blastoderm stage. From the blastoderm stage onward, development was parallel to those eggs which were fertilized by unirradiated sperm. Of the embryos in the groups treated with 30 and 19 krad, 51.3–66.6%, respectively, developed into fully differentiated, normal-appearing, prehatch embryos. The radiation-induced dominant lethal mutations were, generally, expressed very late in embryonic development.