Abstract
The present report dealt with the effect of environmental temperature on radiation induced male sterility in the silkworm Bombyx mori. Evidence has been obtained that sterility induced by irradiation has been influenced to a great extent by the difference of temperature after irradiation whereas no significant effect was indicated when the temperature treatment was given before irradiation. Furthermore, it was revealed that the duration necessary for the effectiveness of the post irradiation temperature to be clearly apparent was about 48hrs after irradiation resulting in the highest percentage of unfertilized eggs at the high temperature (30°C), followed by those at moderate (24°C) and last by the low temperature (18°C) at which the pronounced decrease of unfertilized eggs was observed. In cytological analysis, spermatogonia were found to be most sensitive to radiation and were readily destroyed shortly after exposure. However, the radiation induced sterility in this insect was determined by the fate of spermatocytes at the time of exposure. Almost all the spermatocytes were very changeable according to environmental temperatures of post irradiation, these being death, or functionless abnormal spermatozoa at high temperature or functional normal eupyrene spermatozoa in the case of low temperature treatment. Thus the effectiveness of post irradiation temperature is manifested on the fertility of the irradiated males.
