Latent effect of gamma irradiation on reproductive potential and ultrastructure of males' testes of Culex pipiens(Diptera; Culicidae)

Laboratory male pupae of Culex pipienswere exposed to 23, 41, 74 and 128 Gy doses of gamma radiation according to the LD25,LD50, LD75and LD90calculation, respectively. The inherited deleterious effects of gamma radiation were observed in the F1, F2and F3generations. Levels of sterility index in the F1and F2were higher than those of untreated control but in the F3generation there was a semi-sterility compared with the control. Ultrastructure of normal males' testes of C. pipienswas studied using transmission electron microscopy. Histopathological responses were observed in the irradiated testes of C. pipiens. Gamma radiation had greatly affected the testes, such as (i) rupture, necrosis, degeneration and small vacuoles were reported in the testicular wall (ii) an abnormal distribution of the developmental stages of spermatogonia and spermatocytes leading to a general decrease in the rate of spermatogenesis; and (iii) deformity of sperm inhibitting the movements and the fertility of the sperm led to the decrease in the reproductive potential of C. pipiens. Consequently, these radiation doses are consistent with those used in the already established Sterile Insect Technique (SIT) programmes against Culex pipiens.