STUDIES ON THE MALE STERILITY IN THE SILKWORM, BOMBYX MORI L., INDUCED BY APHOLATE

This report dealt with the effectiveness of apholate, one of alkylating agents, in sterilising the male of the silkworm, Bombyx mori L., with special consideration on cytological consequences after treatment. When the male larvae were administered at the 1st day of the fifth instar with doses more than 300μg per insect they were almost completely sterilized, while no remarkable sterility was shown in the case of the treatment at the middle of the same instar with the same doses of the chemical. From the cytological observations, it has been elucidated that the necrotic cell death of spermatogonia has occurred first after treatment and spermatocytes at the time of treatment transformed into functionless abnormal spermatozoa whereas both spermatids and spermatozoa were highly resistant. From these results, the occurrance of male sterility caused by apholate is interpreted as being due to the transformation of treated spermatocytes into functionless spermatozoa and death of spermatogonia by which the succession of spermatogenesis is halted.