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 crustaceans, the only juvenile hormone-like compound found to date is methyl farnesoate (MF), the unepoxidated form of insect juvenile hormone III. Since MF is hydrophobic, its administration to crustacean larvae in aqueous culture media is problematic. Accumulation of the compound in Artemia cultured in a lipid medium enriched with MF was verified by HPLC, which demonstrated the stability of the compound within the vector. Artemia that were cultured in media containing [³H]MF accumulated 7.27% of the total radioactivity added. About 0.065% of the total radioactivity 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 addition, MF altered larval development by retarding the stage specific morphological features between larval stages 5 and 9. This new method for administering MF may facilitate further studies examining the regulatory role of MF in crustacean larval development and metamorphosis. It may also be instrumental in the administration of other hydrophobic drugs into crustacean larvae.