ECDYSTEROID PROFILES AND VITELLOGENESIS IN PENAEUS-MONODON (CRUSTACEA, DECAPODA)

Ovarian and haemolymph ecdysteroid levels in adult female Penaeus mono don at various stages of vitellogenesis have been studied. The concent ration of free ecdysteroids, predominantly 20-hydroxyecdysone, was max imal in animals with immature (stage 0) ovary, decreased gradually dur ing early vitellogenesis (stage 0 to stage I) and fell sharply during later vitellogenesis (stage I to stage IV). 20-hydroxyecdysone 22-phos phate was identified in stage 0 ovary and in stage 0 and I-II haemolym ph, and 20-hydroxyecdysonoic acid was observed in stage 0 ovary and ha emolymph. Low levels of 20-hydroxyecdysone 22-fatty acyl esters were d etected in stage 0 ovary but did not occur in the haemolymph. A major component of the stage IV haemolymph ecdysteroids was 20-hydroxyecdyso ne 22-acetate. The significance of the results is discussed.