Alteration of Molting-Related Metabolites in the Carapace of Kuruma Prawn (Penaeus japonicus) Juveniles After Fipronil Exposure.

Abstract

In aquatic arthropods, molting is essential for normal development. An earlier study showed that 3-phosphoglycerate (3PG) and phosphoenolpyruvate (PEP), which are present in the exoskeleton, play important roles in its calcification. Under normal culture conditions, we found higher levels of 3PG and PEP at the pre-molt stage than that at the post-molt stage in the carapace of kuruma prawn juveniles (Penaeus japonicus). In subsequent experiments, exposure of environmentally relevant concentrations of fipronil (0.1, 0.05, and 0.025 µg L^-1) for 24-96 h resulted in significant decreases in 3PG and PEP in the exposure group. Furthermore, we found higher internal insecticide concentrations in molted prawns than those in unmolted prawns. Given that molting requires a higher amount of energy, these changes are indicative of the allocation of more and less energy for detoxification and molting, respectively, which may contribute to the mitigation of fipronil bioconcentration.