Abstract: 【Aim】 Insulin-like peptide (Ilp) is located in the upstream of insulin signaling pathway and plays a key role in regulating sugar metabolism. This study aims to explore the function of Ilp in regulating the trehalose metabolism balance in the brown planthopper, Nilaparvata lugens. 【Methods】 The expression of Ilp genes in the 5th instar nymphs of N. lugens was inhibited by RNAi technology, and the phenotype and ovarian development of the female adults of N. lugens were observed after RANi.The changes in the contents of trehalose, glycogen and glucose and the trehalase activity were determined by biochemical methods, and the changes in the expression levels of trehalase genes (TRE1-1, TRE1-2 and TRE2) and trehalose synthase genes (TPS1 and TPS2) in the 5th instar nymphs of N. lugens at 48 h and 72 h after RNAi were tested by qPCR. 【Results】 The dsRNA effectively inhibited the expression of Ilp genes and resulted in abnormal wing in N. lugens, and the injection of dsIlp3 and dsIlp1+dsIlp2+dsIlp3+dsIlp4 caused underdeveloped ovaries in the 2-day-old female adults of N. lugens. The glucose levels were significantly increased at 48 h after injection of dsIlp1-4 and dsIlp1+dsIlp2+dsIlp3+dsIlp4, respectively, and the glycogen levels were also significantly increased at 48 h after injection of dsIlp2, dsIlp3 and dsIlp4, respectively. The trehalose content was significantly increased at 48 h after injection of dsIlp3 and dsIlp4, respectively, while the trehalose content decreased significantly at 72 h after inhibition of Ilp2 and Ilp4, respectively, and increased significantly both at 48 h and 72 h after injection of dsIlp1+dsIlp2+dsIlp3+dsIlp4. In addition, the soluble trehalase activity increased significantly at 72 h after injection of dsIlp1+dsIlp2+dsIlp3+dsIlp4, while the membrane-bound trehalase activity decreased significantly at 72 h after injection of dsIlp3, dsIlp4 and dsIlp1+dsIlp2+dsIlp3+dsIlp4, respectively. The expression levels of TRE1-1, TRE1-2, TRE2, TPS1 and TPS2 were significantly decreased after injection of dsIlp1, dsIlp2 and dsIlp4, respectively. 【Conclusion】 Silencing of Ilp genes has an inhibitory effect on the development and reproduction of N. lugens, and can increase the contents of glucose and glycogen, downregulate the expression of genes of trehalase and trehalose synthase, and increase the soluble trehalase activity, thus regulating the trehalose metabolism in N. lugens.

Key words: Nilaparvata lugens, insulin-like peptide, insulin signaling pathway, trehalose metabolism, RNA interference