Abstract:
 The spiralling whitefly (SWF), Aleurodicus dispersus Russell, is an important agricultural and forest pest. In this study, we detected and analyzed the infection status and the gene sequences of three secondary endosymbionts Cardinium, Arsenophonus and Wolbachia in the SWF populations of 16 districts in Hainan province, southern China, based on 16S rDNA of Cardinium and Arsenophonus and wsp gene of Wolbachia. The results showed that the spiraling whitefly was infected by both Cardinium and Arsenophonus. The infection rate of Arsenophonus was 100% in A. dispersus populations from Ledong, Lingshui and Chengmai, and 66.7% in the populations from Sanya, Qiongzhong and Lingao, while there is no infection of Arsenophonus in the populations from Danzhou, Wuzhishan and Wanning. Similarly, the infection rate of Cardinium was 100% in A. dispersus populations on host plants Pterocarpus indicus in Qionghai and Baisha and Psidium guajava in Sanya, and less than 66.7% in the populations on other host plants. Among the 43 populations of A. dispersus detected, 40 and 31 populations were infected with Arsenophonus and Cardinium, with the infection rates of populations of 93.0% and 72.1%, respectively. Among the tested 120 individuals for detecting Arsenophonus infection and 93 individuals for detecting Cardinium infection, the numbers of infected individuals by Arsenophonus and Cardinium are 105 and 70, with the infection rate of individuals of 87.5% and 75.3%, respectively. The infection rate of populations and the infection rate of individuals by Wolbachia were 2.3% and 0.8%, respectively. The Cardinium 16S rDNA gene of different populations of A. dispersus in Hainan shares the same sequence, and has a high identity (97.6%) with the Cardinium 16S rDNA gene of Bemisia tabaci. The Arsenophonus 16S rDNA gene of different populations of A. dispersus in Hainan also shares the same sequence, with 85.1% identity with the Arsenophonus 16S rDNA gene in A. dispersus population in Canary Islands. In addition, Wolbachia in A. dispersus belongs to B group according to the analysis of wsp genes, and this is the first record in China.

Key words: Aleurodicus dispersus, Cardinium, Arsenophonus, Wolbachia, infection rate, phylogenetic analysis