Abstract: There are about 5 kinds of endosymbionts in Bemisia tabaci (Gennadius) complex including primary endosymbionts, secondary endosymbionts, Wolbachia, Candidatus Fritschea bemisiae and Cytophaga-like-organism. Phylogenetic analysis showed that primary endosymbionts in B. tabaci complex could be divided into two clades based on the 16S rDNA sequences. The phylogeny of primary endosymbionts in B. tabaci was not strictly congruent with that of their host B. tabaci. Secondary endosymbionts in B. tabaci complex could be divided into three clades based on the 16S rDNA sequences, and horizontal transmission and/or multiple infections might have occurred in these secondary endosymbionts. The distribution of the endosymbionts in B. tabaci biotypes was different, and some peculiar primary and secondary endosymbionts were found in B. tabaci Biotype B. Wolbachia, Candidatus Fritschea bemisiae and Cytophaga-like-organism were not found or scarcely found in B. tabaci Biotype B. Finally the biological implications of different endosymbionts for B. tabaci and future research directions are discussed.

Key words: Bemisia tabaci complex, endosymbionts, diversity, distribution