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

Laboratory male pupae of Culex pipiens were exposed to 23, 41, 74 and 128 Gy doses of gamma radiation according to the LD 25, LD 50 , LD 75 and LD 90 calculation, respectively. The inherited deleterious effects of gamma radiation were observed in the F 1 , F 2 and F 3 generations. Levels of sterility index in the F 1 and F 2 were higher than those of untreated control but in the F 3 generation there was a semi-sterility compared with the control. Ultrastructure of normal males' testes of C . pipiens was 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 .