TESTICULAR ECDYSTEROIDS IN THE SILKMOTH, BOMBYX-MORI

Testicular and haemolymph ecdysteroid levels in the silkmoth, Bombyx: mori, were measured from the beginning of the last larval instar until 1 day before adult eclosion by Radioimmunoassay. The amount of ecdyst eroids in testes just after the 4th ecdysis was about 150 pg/pair and rapidly decreased by Day 2. Afterwards, ecdysteroids titre increased g radually. An abrupt increase of ecdysteroids titre was observed during the wandering stage. After pupation, the level of ecdysteroids became increasingly detectable on Day 3 of the pupal stage and it decreased rapidly thereafter. The main component of ecdysteroids in larval teste e was 20-hydroxyecdysone (about 2/3 of the total) and ecdysone. An unk nown ecdysteroid which eluted at the same retention time as authentic 20-hydroxyecdysone-22-acetate was also detected. The fluctuation patte rn of ecdysteroids in the haemolymph closely paralleled that of the te stes, although the titres were much higher than those of testes.