Tannins are polyphenols and defensive molecules occurring widely in plants. Dietary tannin may bind digestive enzymes of herbivores and affect them by reducing digestibility. In lepidopteran caterpillars, lysophosphatidylcholine (lysoPC), known as surfactants present in the guts, are thought to interfere with tannin protein interactions. However, details of biosynthetic pathways of lysoPC in caterpillars have not been paid attention. Here, we investigated biosyntheses of lysoPC in Spodoptera litura larvae. S. litura larvae were fed on artificial diets enriched with [U-(13)C]linolenic acid for 3 h, and then phospholipids in the gut contents were analyzed by LCMS-IT-TOF. Labeled linolenic acid was incorporated into lysoPC as well as diacyIPC, diacylphosphatidylethanolamine (diacylPE) and diacylphosphatidylinositol (diacylPI). Detailed investigation on the biosynthesis revealed that [U-(13)C]linolenic acid was incorporated into phospholipids in gut tissues and then the biosynthesized phospholipids were released to the gut lumen, and then some of diacyIPC were hydrolyzed to lysoPC in the gut lumen. When S. litura larvae were fed on artificial diets enriched with tannic acid, a significant increase in the activity to produce diacyIPC in the gut tissues was observed. The activated diacyIPC production leading to an increase of lysoPC in the larvae might be the adaptively-tuned mechanisms against plant tannins. (c) 2010 Elsevier Ltd. All rights reserved.