Testicular Ecdysteroids in the Silkmoth, Bombyx mori.

Abstract

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 ecdysteroids in testes just after the 4th ecdysis was about 150 pg/pair and rapidly decreased by Day 2. Afterwards, ecdysteroids titre increased gradually. 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 testes was 20-hydroxyecdysone (about 2/3 of the total) and ecdysone. An unknown ecdysteroid which eluted at the same retention time as authentic 20-hydroxyecdysone-22-acetate was also detected. The fluctuation pattern of ecdysteroids in the haemolymph closely paralleled that of the testes, although the titres were much higher than those of testes.