Sterilization of the male silkworm, Bombyx mori L. by the high temperature environment

• Published in: The Journal of Sericultural Science of Japan Vol. 41; no. 1; pp. 51 - 56
• Main Authors: SUGAI, Etsuji, HANAOKA, Akira
• Format: Journal Article
• Language: English; Japanese
• Published: The Japanese Society of Sericultural Science 1972
• ISSN: 0037-2455; 1884-796X
• DOI: 10.11416/kontyushigen1930.41.51

Sterilizing effect of high temperature environment (32°C, 96hrs) on the male silkworm, Bombyx mori was studied with special reference to their sensitivity in different developmental stages and in races used. Furthermore, the function of prostatic gland for sperm activation was investigated in regard to the sterilization. The results obtained are summarized as follows: 1) The sensitivity of male Bombyx mori to the sterilizing effect of high temperature was the highest at the prepupal stage, from spinning to pupation, and the next was the pupal period, whereas no sterilizing effect of high temperature was observed in the larval period from hatching to the middle of the 5th instar. 2) The male sterilization at prepupal period increased with times exposing to high temperature (32°C) and they were completely sterilized when treated continuously for 72 hrs (Daizo race) or 96 hrs (Konjiki race) after the start of spinning. On the contrary, such sterilization decreased as the time passed before the treatment and no sterilization occurred when Daizo race was treated 48 hrs after the start of spinning. 3) The sterilizing effect of high temperature at the prepupal stage was noticeable in all races used in this experiment, though the sterilizing response varied with races. 4) Copulatory organs of sterilized male moths treated at prepupal stage exhibited no visible abnormality. However, the amount of spermatozoa in the bursa copulatrix of females mated with the treated males was reduced considerably and their motility was also arrested. No spermatozoa were found in the receptaculum seminis of copulated females. 5) When the prostatic gland from sterilized male moth was added to spermatozoa from the ampulla ductus deferentis of normal male, the spermatozoa were strongly activated and their active motility was maintained even 2 hrs later as well as those added with the prostatic gland from normal male. On the contrary, when the prostatic gland from normal male moth was added to spermatozoa from the ampulla ductus deferentis of sterilized moth, the sperm activation occurred weakly and their motility stopped within 2 hrs as those added with the prostatic gland from sterilized male moth. From these findings, it is concluded that the sterility induced by high temperature environment is not caused by the abnormal function of the prostatic gland, the sperm activator, but due to the abnormality of the spermatozoa themselves.