THE INFLUENCE OF AN INSECT GROWTH-REGULATOR ON THE LARVAL DEVELOPMENT OF THE MUD CRAB RHITHROPANOPEUS-HARRISII

Effects of the juvenile hormone analogue (S)-methoprene on the larval development and survival of the estuarine mud crab Rhithropanopeus harrisii were examined in the laboratory. Crab larvae continuously exposed to 1000 mug (S)-methoprene litre-1 did not survive beyond zoeal stage I. With continuous exposure to 100 mug (S)-methoprene litre-1, mortality significantly increased through all larval stages except or zoeal stage II, and developmental duration significantly increased through all zoeal stages but not the premetamorphic megalopa. No supernumerary larval stages occurred with exposure to (S)-methoprene. Rhithropanopeus harrisii larvae appear to be more sensitive to the single isomer formulation (S)-methoprene than to the double isomer formulation, (R,S)-methoprene, used in previously documented studies.