Comparative gamma-radiation sensitivity of Glossina tachinoides Westw, Glossina fuscipes fuscipes Newst and Glossina brevipalpis Newst (Diptera, Glossinidae)

The effect of gamma-radiation doses ranging between 10 and 180 Gy on 4-6-day-old adult males of Glossina tachinoides, Glossina fuscipes fuscipes and Glossina brevipalpis was studied. Fecundity of their mates was reduced by 95% following exposure to 120, 80-100 and 50 Gy of adult male G. tachinoides, G. f. fuscipes and G. brevipalpis respectively. Insemination ability of the males and sperm motility were not adversely affected by the radiation treatment. The higher proportion of dominant lethals in the sperm of the three species with increasing radiation doses was reflected in the reproductive status of the female mates, i.e. an increasing percentage of females showing imbalances between intrauterine content and ovarian development (females with an empty uterus due to expulsion of a dead embryo after embryonic arrest or a degenerating egg in utero) and an acceleration in follicle development associated with successive unsuccessful cycles. In the F-1 progeny of all treated groups, no significant bias of the sex ratio was found. The average life span of G. tachinoides and G. f. fuscipes males treated with doses of greater than or equal to 80 Gy and of G. brevipalpis males treated with doses >140 Gy was significantly reduced as compared with untreated controls. Male G. brevipalpis treated with doses ranging between 10 and 40 Gy, however, showed a significant radiation induced increase in average life span.