Abstract: 【Aim】 To understand the bacteria species in saliva of adults of the brown planthopper, Nilaparvata lugens， by identifying the bacterial proteins in their saliva. 【Methods】 Saliva of N. lugens adults was collected by stretching two layers of Parafilm with sucrose diet. Protein solution was subjected to electrophoresis after concentration by ultrafiltration. Protein identification was conducted by liquid chromatography-electrospray ionisation-tandem mass spectrometry (LC-ESI-MS/MS) analysis, and the spectra were searched against the Uniprot database of bacterial protein to identify the bacterial proteins in saliva. 【Results】 Thirty five proteins of twenty-two species of bacteria, mainly related to energy metabolism, protein folding and synthesis and amino acid metabolism, were identified in saliva of N. lugens adults. These bacteria belong to Proteobacteria, Actinobacteria and Firmicutes, and most are from Proteobacteria. 【Conclusion】 The endosymbiont bacteria in N. lugens, whose proteins were identified, may play an important role in the life history of this insect.

Key words: Nilaparvata lugens, saliva, bacterial protein, endosymbiont bacteria, LC-ESI-MS/MS