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

This study examines the effects of Fenoxycarb(R) on larval growth, and lipi d class and fatty acid composition in first crabs of the mud crab Rhithropa nopeus harrisii reared through total larval development in nominal water co ncentrations from 1 to 100 mug/l. In first crabs of R. harrisii, dry weight (mug) decreased significantly (P < 0.05) from 228.8 +/- 38.2 <mu>g (n = 9) in the controls to 131.8 +/- 10.1 mug (n = 4) in animals exposed throughou t larval development to 100 mug/l. A significant (P < 0.05) reduction was f ound between total lipid content in the controls and first crabs reared at concentrations greater than 50 <mu>g/l. In relative terms (% dry weight), d ifferent lipid classes predominated in the controls and the various fenoxyc arb exposure concentrations. There were no significant (P > 0.05) differenc es among the treatment groups in phospholipid level, while the triglyceride content was significantly lower in crabs exposed to 10 and 100 mug/l. No s ignificant differences in the percent of free fatty acids were found in cra bs exposed to 1-10 mug/l and the controls. Free sterols in crabs exposed to concentrations higher than 10 mug/l were below the detection limit. Contro l animal fatty acid profiles were dominated by palmitic, stearic, and oleic acid, accounting for 48% of total fatty acids (TFA). The fatty acid compos ition of crabs exposed to 100 mug/l significantly (P < 0.05) differed from the controls. The results suggest that fenoxycarb has substantial effects o n growth, lipid class and fatty acid composition in developing larvae of R, harrisii at water concentrations greater than 10 <mu>g/l. (C) 2000 Elsevie r Science Inc. All rights reserved.