Study On Infetion And Impact Factors Of Endosymbionts Wolbachia In Bemisia Tabaci

Bemisia tabaci (Gennadius) (Hemiptera:Aleyrodidae) is a considerable globally distributed pest. One of the key endosymbionts in B. tabaci is Wolbachia, an a-proteobacterium implicated in many important biological processes. Previous studies indicated that the infection frequency of Wolbachia in Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) varied greatly among populations in different areas. However, little is known about what factors influence prevalence of the Wolbachia in B. tabaci. In this study,25 field populations were collected from different locations in China and 1161 individuals were screened for the presence of Wolbachia using a nested PCR-based method which targets the wsp gene to confirm Wolbachia infection status. The prevalence of Wolbachia ranged from 1.54% to 66.67% within the 25 field populations and infection frequency of Wolbachia was affected significantly by the B. tabaci putative species, the infection frequency (54.55%) of Wolbachia of native species was significantly greater than that of MED (21.36%) and MEAM1 (15.15%). However, no significant differences were found either among host plants or between sexes. Six Wolbachia strains were found and clustered into four distinct clades with phylogenetic analyses. Furthermore, Wolbachia of B. tabaci have close relationship with those from other host species, Liriomyza trifolii, Sogatella furcifera, Nilaparvata lugens and Culex pipiens. The results demonstrated that the variation and diversity of Wolbachia in B. tabaci field populations and the application of nested PCR extended our knowledge on Wolbachia infection of B. tabaci, especially the invasive whiteflies.1 The selection of detection methods of Wolbachia infection in B. tabaci.We have compared conventional PCR target Wolbachia surface protein gene (wsp) and 16S rDNA. Except using universal primers 81F/691R and 16S-F/R, we also tried to use the specific primers 16S315f/628r designed by Li et al.(2007). We have found false negative or positive were frequently encountered in detecting Wolbachia in B. tabaci. Finally, we chose nested PCR, which target Wolbachia surface protein gene (wsp), to detect Wolbachia in B. tabaci.2. Relation between Wolbachia infection of B. tabaci field populations and different putative species, host plants and others.Totally 1161 whitefly adults were collected frome 13 kinds of host plants in in Jiangsu and Zhejiang provinces in southeastern of China. We have detected Wolbachia infection of B. tabaci and analyzed the relationship between Wolbachia infection in field populations and possible affect factors such as, host putative cryptic species, host plants, geographic location and sex. Though one way ANOVA analysis, our date revealed that there were significant differences between Wolbachia infection and B. tabaci putative species and no significant differences were found either among host plants or between sexes.3. Phylogenetic analysis of Wolbachia in B. tabaci field populationsWe have amplified Wolbachia wsp gene of B. tabaci field populations using specific primers. The length of Wolbachia wsp gene fragments is 500 bp approximately. After analysis of sequences, we found B. tabaci field populations infected with six Wolbachia strains, we named them:wBtabYZ1 (KJ648498), wBtabHZ2 (KJ648499), wBtabNJ3 (KJ648500), wBtabNJ4 (KJ648501), wBtabJH5 (KJ648502) and wBtabYC6 (KJ648503). wBtabYZl and wBtabHZ2 strains are found in most populations, while, wBtabNJ3 and wBtabNJ4 are found only Nanjing laboratory population and wBtabJH5 and wBtabYC6 were found only in Jinhua and Yancheng populations respectively. Phylogenetic analysis showed that homology of Wolbachia wsp gene in B. tabaci field populations is high, and close with other host species such as Liriomyza trifolii, Sogatella furcifera, Nilaparvata lugens and Culex pipiens.