Sterilization and sperm competition in insects with reference to pest control measures using reproductive behavior.

点击翻译按钮获取中文摘要

Method to count the number of sperm in spermathecae of the melon fly was established, and using this method, it was found that longevity of melon fly sperm in spermathecae is shorter than that of other insects so far known. Due to this short life span of sperm, precedence of last male's sperm for fertilization rise as duration between first and second copulations increases.Not only copulation with normal (unirradiated) males but also that with sterile (irradiated) males inhibits remating of females. It was shown that copulation with sperm-exhausted sterile males can inhibit remating of females; this is contrasting to case of Drosophila melanogaster, where existence of sperm in spermathecae is necessary to inhibit remating.Experiments also suggested that the inhibition of remating is a females strategy.Examinations of testis and spermathecae with an electronic microscope showed that gamma-ray irradiation at a dose which has been used for the melon fly eradication project induce not only dominant lethal mutation in sperm but also physiological and morphological damage to the notable fraction of the sperm; an important result for future development of sterile male technique to eradicate insect pests.