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|Title:||Some biological and histopathological effects of gamma radiation on the gonads of the Oriental fruit fly, Dacus dorsalis Hendel|
|Authors:||Manoto, Eugenia C.|
|Keywords:||Oriental fruit fly|
Gamma rays -- Physiological effect
|Abstract:||The feasibility of utilizing radiation sterilization for the control of the Oriental fruit fly, Dacus dorsalis Hendel, was the general consideration of this study. It included a comparison of radiation effects on flies when treated as 8-day-old pupae or as 3-day-old adults. Treatment with 5 or 10 Krad of gamma radiation resulted in an atrophied condition of both testes and ovaries when treated as either pupa or adult. In the testes, such condition was induced by the death of the stem cells, the spermatogonia, and by the degeneration of pycnotic spermatocytes and spermatids and an eventual resorption of testicular contents. Similarly, necrosis of oogonial cells was evident in the ovaries. The radiosensitivity of the male germ cells was dependent upon the stage of cell division. Irradiation produced an abortive cell division among the spermatogonial cells while cells undergoing meiosis became pycnotic. The spermatids and immature sperm bundles, which do not undergo cell division, were relatively resistant to radiation effects when treated with 5 Krad. The ovary was found to be more sensitive to radiation than the testis when the same dose and age levels were used. Irradiation of both pupae and adults inhibited ovarian growth due to oogonial cell killing. As a consequence of oogonial death, the mitotic activity of these cells was completely stopped. The endomitotic activity in the nurse cells created a radiosensitive situation among the treated females forming pycnotic nurse cells. There was no recovery in both spermatogenesis and oogenesis even at 44 days after treatment of either pupae or adult fruit flies irradiated with 5 or 10 Krad. This result indicated that sterility in both males and females was permanent. Radiation reduced the amount of sperm transferred by a l5-day-old male treated with 10 Krad during the pupal stage. This was possibly a consequence of death of spermatogonial cells resulting in aspermia. However, males irradiated during the adult stage and those irradiated with 5 Krad at either stage were able to transfer sperm longer than those treated with 10 Krad during pupal stage. Studies evaluating mating performance of male flies indicated that both treated and nontreated males in a 3:1 ratio, except those treated with 10 Krad in the pupal stage, competed with equal success with normal females. Irradiation reduced fertility of eggs laid by females mated with treated males. A dose of 5 Krad induced about 99.5% dominant lethality among the sperm of testes when flies were treated as late pupae and about 91.9 to 99.8% lethality when males were treated as 3-day-old adults with 5 and 10 Krad, respectively. In addition, the fecundity of the females was affected by radiation treatment so that none or very few eggs were laid by treated females. Certain biological effects of radiation sterilization on longevity were also evaluated. Mortality studies on irradiated flies showed that sterilization with 5 or 10 Krad did not affect the longevity of adults, at least for 90% of the population. These findings indicate that a sterilization procedure with 3-day-old adults of 10 Krad may be further explored with a view to employing it in a control program. Alternatively, one may utilize irradiation of 8-day-old pupae with 5 Krad.|
Thesis (Ph. D.)--University of Hawaii at Manoa, 1973.
Bibliography: leaves -125.
xi, 125 l illus., tables
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|Appears in Collections:||Ph.D. - Entomology|
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