Growth, lipid class and fatty acid composition in juvenile mud crabs (Rhithropanopeus harrisii) following larval exposure to Fenoxycarb®, insect juvenile hormone analog

Abstract

This study examines the effects of Fenoxycarb® on larval growth, and lipid class and fatty acid composition in first crabs of the mud crab Rhithropanopeus harrisii reared through total larval development in nominal water concentrations from 1 to 100 μg/l. In first crabs of R. harrisii, dry weight (μg) decreased significantly (P<0.05) from 228.8±38.2 μg (n=9) in the controls to 131.8±10.1 μg (n=4) in animals exposed throughout larval development to 100 μg/l. A significant (P<0.05) reduction was found between total lipid content in the controls and first crabs reared at concentrations greater than 50 μg/l. In relative terms (% dry weight), different lipid classes predominated in the controls and the various fenoxycarb exposure concentrations. There were no significant (P>0.05) differences among the treatment groups in phospholipid level, while the triglyceride content was significantly lower in crabs exposed to 10 and 100 μg/l. No significant differences in the percent of free fatty acids were found in crabs exposed to 1–10 μg/l and the controls. Free sterols in crabs exposed to concentrations higher than 10 μg/l were below the detection limit. Control animal fatty acid profiles were dominated by palmitic, stearic, and oleic acid, accounting for 48% of total fatty acids (TFA). The fatty acid composition of crabs exposed to 100 μg/l significantly (P<0.05) differed from the controls. The results suggest that fenoxycarb has substantial effects on growth, lipid class and fatty acid composition in developing larvae of R. harrisii at water concentrations greater than 10 μg/l.