Transport and Utilization of Lipids in Insect Flight Muscles*

In migrating lepidopteran and orthopteran insects, lipid is the preferred fuel for sustained flight activity. Diacylglycerol is delivered by lipophorin to the flight muscle and hydrolyzed to free fatty acid and glycerol. After penetrating the plasma membrane by an unknown mechanism, fatty acids are bound by the intracellular fatty acid binding protein (FABP) and transported through the cytosol. After their conversion to acyl-CoA esters, the fatty acids enter the mitochondrial matrix via the carnitine shuttle for subsequent β-oxidation. This article reviews the current knowledge of lipid metabolism in insect flight muscle, with particular emphasis on the structure and function of FABP and its expression during locust development and flight.