[Determination of the ecdysone level in the molting cycle of the crab, Carcinus moenas: comparison between healthy individuals and those parasitized by Sacculina carcini].

Radioimmunoassay is performed for a quantitative study of ecdysone in Carcinus moenas. Two periods can be determined in the moulting cycle. In haemolymph from ecdysis until beginning D0 stage, the moulting hormone content is not very high; from D0 stage until D4 stage, the hormone titer rises considerably. We can observe a similar rise in hormone content in both haemolymph and Y organ during the premolt stages. In sacculinized Crabs, the determined values of ecdysone in haemolymph and in Y organ are lower than those determined in healthy animals at the same stage.