Abstract: PCR amplification of 16S rDNA with universal primers was conducted to detect the symbiotic bacteria of the rice brown planthopper, Nilaparvata lugens (Stål) . Analysis of the sequences showed that the brown planthoppers contain the symbiotic bacteria Arsenophonus，which has close relationship with Arsenophonus symbiont of Psyllidae and Aleyrodidae based on phylogenetic analyses. Two 16S rDNA sequences of Arsenophonus in N. lugens with different sizes were amplified, one is 1 504 bp and the other is 547 bp in length. The shorter one is the deleted product of the longer one by loss of its internal region of 957 bp. With two primers redesigned based on the above 16S rDNA sequences, the result of PCR amplification showed that the two different fragments existed in various host-associated populations and different geographic populations of N. lugens. Using 23S rDNA specific primers, the genus Arsenophonus was found in all the tested populations of N. lugens, but not in the host rice plant. The TN1 population carried significantly higher amount of Arsenophonus bacteria than the Mudgo population and ASD7 population assessed by quantitative real-time PCR. This is the first report of Arsenophonus bacteria from N. lugens.  

Key words: Nilaparvata lugens, symbiotic bacteria, Arsenophonus, 16S rDNA, phylogenetic relationship