Ecdysteroid titres during postembryonic development of Sarcophaga bullata (Sarcophagidae: Diptera)

The level of ecdysteroids in Sarcophaga bullata was determined by radioimmunoassay (RIA) from the time of larviposition (0 hr) until adult eclosion. Five distinct peaks of ecdysteroid activity were recorded. The first two, which occurred midway through the duration of the stadia (14 and 30 hr, respectively), resulted in larval/larval moults (24 and 44 hr). The third peak of ecdysteroid activity commenced at 131 hr and was associated with formation of the white prepuparium. The fourth peak was sustained over a long time period (from 79 hr post pupariation to 120 hr) and resulted in pupal/adult apolysis and the definition of the adult form. The last elevation of the ecdysteroid titre at approx. 160 hr post pupariation) was associated with the synthesis and secretion of adult cuticle.