ADMINISTRATION OF METHYL FARNESOATE THROUGH THE ARTEMIA VECTOR, AND ITS EFFECT ON MACROBRACHIUM-ROSENBERGII LARVAE

We have developed a method for the administration of juvenile hormone- like compounds into crustacean larvae through a live food vector, the brine shrimp Artemia, commonly used in prawn aquaculture. In crustacea ns, the only juvenile hormone-like compound found to date is methyl fa rnesoate (MF), the unepoxidated form of insect juvenile hormone III. S ince MF is hydrophobic, its administration to crustacean larvae in aqu eous culture media is problematic. Accumulation of the compound in Art emia cultured in a lipid medium enriched with MF was verified by HPLC, which demonstrated the stability of the compound within the vector. A rtemis that were cultured in media containing [H-3]MF accumulated 7.27 % of the total radioactivity added. About 0.065% of the total radioact ivity added was found in 20 M. rosenbergii larvae fed on the enriched Artemia. MF freshly administered daily to M. rosenbergii larvae caused a retardation of larval growth, manifested by carapace length. In add ition, MF altered larval development by retarding the stage specific m orphological features between larval stages 5 and 9. This new method f or administering MF may facilitate further studies examining the regul atory role of MF in crustacean larval development and metamorphosis. I t may also be instrumental in the administration of other hydrophobic drugs into crustacean larvae.