In animals, glycoproteins are known to be important for a multitude of biological processes such as cell signaling, immunological recognition and the unique process of insect metamorphosis. However, our knowledge of insect glycoproteins is limited and is restricted to the model insect Drosophila melanogaster. In this project, we will study the N-glycosylation of proteins in the hemimetabolous sap-sucking brown planthopper Nilaparvata lugens. N. lugens has emerged as a model insect with its genome sequence recently available and successful functional studies reported with molecular techniques such as RNA interference (RNAi). Moreover, N. lugens is the most destructive pest insect in cultivated rice worldwide. The project will focus on the N-glycosylation profile and the biological functions of N-glycoproteins in the development of N. lugens with special attention on the unique process of insect metamorphosis. The N-glycans and N-glycosylated proteins in different developmental stages will be identified with advanced mass spectrometry technologies. Then, functional studies on selected stage-specific N-glycans and N-glycosylated proteins with RNAi will reveal their biological importance in insect development. Since N-glycoproteins are often targets of plant lectins that show insecticidal activity, a better understanding of the N-glycan diversity in N. lugens will also allow a broader insight that can contribute to the elaboration of new pest control strategies in the future.