Abstract:  There are a large number of symbionts in the brown planthopper (BPH), Nilaparvata lugens, and these symbionts exhibit the diversity not only in their species but also in their functions on hosts. Up to now, 19 and 53 genera of symbiotic fungi and bacteria (sequencing abundance＞0.1%), respectively, have been identified by using molecular biological methods and high-throughput sequencing technology, but plenty of symbionts remain unknown in taxonomic status due to technical limitations and their unculturable characteristics. Symbionts play vital roles in the life activities of BPH including the growth, development, reproduction, nutritional metabolism, resistance variation and immune function, and various symbionts have different functions. The symbiotic fungi are mainly involved in the synthesis of sterols and essential amino acids, while the symbiotic bacteria mainly take part in the synthesis of vitamins. The symbionts have important influence on the virulence variation, the development of high resistance to insecticides and the reproduction of host BPH, but the molecular mechanisms have not yet been clarified. In this article we reviewed the diversity of symbionts of BPH and prospected the focal points of future research including the species identification of symbionts of BPH, the functional studies of specific and single species of symbionts, the diffusion pathway, diffusion species and regulatory mechanism of symbionts in different tissues of BPH, and the control of BPH using symbionts as targets.

Key words: Nilaparvata lugens, symbionts, species diversity, functional analysis, taxonomic status, biocontrol