Effects of a Juvenile Hormone Mimic on Male and Female Gametogenesis of the Mud-Crab, Rhithropanopeus harrisii (Gould) (Brachyura: Xanthidae)

1. Effects of ingestion and topical application of 1.30 ppm methoprene, an insect juvenile hormone (JH) mimic, include gametogenesis disorders in both male and female mud-crab Rhithropanopeus harrisii. 2. Progressive inhibition of vitellogenesis and stimulation of spermatogenesis take place after a short exposure time (12-15 days), whereas a longer period (between 30 to 45 days) promotes inhibition of both spermatogenesis and vitellogenesis. Such modifications demonstrate the chemosterilizing action of methoprene on crustaceans. 3. Stoppage of vitellogenesis is characterized by a blockage of oocytes at terminal previtellogenesis and proliferation of the follicle cells involved in vitellogenic oocyte lysis. Spermatogenic degeneration begins with the amalgam of spermatocyte clusters in meiotic prophase and pycnosis of gonia. 4. Analogies between these results and those obtained from experiments involving androgenic gland implantations or the consequences of their hyperfunctioning are discussed.