Radiosensitivity of Different Stages of Spermatogenesis in the Boll Weevil134

Abstract

All cell stages of spermatogenic cells are found in the adult boll weevil, Anthonomus grandis Boheman. We irradiated males and then allowed them to mate daily with successive groups of virgin females. Variations in fertility and in numbers of sperm produced were used as a basis for measuring changes in resistance of germ cells to the induction of dominant lethal mutations and to cell death. As expected, the various cell stages were not uniformly resistant. Sperm utilized by males immediately after irradiation were mature at the time of treatment. High doses of gamma irradiation were required to suppress fertility, indicating a high degree of resistance to the induction of dominant lethal mutations. Matings between the 3rd and 4th days after irradiation produced the fewest progeny. Sperm maturing at this time probably developed from irradiated spermatids; this cell stage was about 10 times more sensitive than mature sperm. Progeny development increased with the matings 6-7 days after irradiation, indicating that the early cell stages were relatively resistant as far as dominant lethal mutations were concerned. However, these immature cell stages were readily destroyed by irradiation. Sperm production between the 5th and 8th days after treatment with 2500 rad (sperm arising from cells treated 5-8 days prior to maturity) was reduced by about 70%, indicating extensive cell destruction even with a substerilizing dose.