The Modification by X-Irradiation of the Life Span of Haploids and Diploids of the Wasp, Habrobracon SP

Haploid males, diploid males, and diploid females of the wasp, Habrobracon sp., were x-irradiated as larvae-incocoons, white pupae, and adults, and their adult life span was obtained. The median life span for nonirradiated adults was 62 days for haploid males and diploid males, 92 days for diploid females fed on honey-water, and 40 days for diploid females fed on Ephestia larvae. The difference in life span is related to sex but not to genome number and suggests that the normal aging process is not due to an accumulation of somatic mutations. Although a nutritional factor may be involved in the life span of females, this caanot be resolved by the present experiments. since females that are fed honey-water do not lay eggs, whereas females that are Ephestia-fed lay eggs throughout their lives. Diploid males irradiated as adults (10000 to 50000 r) have a longer life span than comparable haploid males. Diploid males and diploid females show similar decreases in life span relative to their controls. Radiation-induced decrease in life span is markedly influenced by genome number but not by sex. This suggests that the decrease in life span by x irradiation is due to damage of a genetic nature. Themore » differential sensitivity of haploid and diploid adults to x irradiation indicates that gene action is taking place in the adult stage and in nondividing cells. Pupae after exposure to 10000 and 15000 r are not inhibited in their ability to develop into structurally normal adults. These adults, however, show a decrease in life span. Haploid males have a markedly shorter life span than diploid males. Diploid males are similar to diploid females In decreased life span. This differential sensitivity is due apparently to genetic damage which becomes observable for groups of older adults. Larvae after exposure to 2000 r are able to develop into structurally normal adults. These adults, however, show a decrease in life span. Haploid males are similar to honey-fed females. Ephestia fed females show a considerable decrease in life span for reasons that are not clear. The differential sensitivity of haploids and diploids is different for the larval, pupal, and adult stages. This is probably related to different types of genetic injury such as effects on cell division and on gene action occurring in different stages of development. (auth)« less