Endosymbionts could facilitate their hosts to acquire additional nutrition, product more offsprings, improve their adaptability to temperature and enhance their insecticide resistance. They play a dominant role in maintaining the balance of population dynamics of insects. Here, we analysised the differences in species and number of the endosymbiont between various cryptic of Bemisia tabaci by metagenomics technology, and investigated the potential function of the dominant endosymbiont of Bemisia tabaci. Furthermore, the effect of dominant bacteria on life history and development of the Bemisia tabaci was studied. The main results were showed as follows:(1) There were significant differences in the species and number of the endosymbiont between various cryptic of Bemisia tabaci. We constructed a set model to describe the comparative symbiont compositions between B.tabaci MEAM1 and MED at the level of species, genus, and family, respectively. There were 15,26,19 taxa in terms of species, genus and family occurring in MEAM1 rather than in MED exclusively, respectively; while there were 52,60,37 taxa in terms of species, genus and family occurring in MED rather than in MEAM1, respectively; B. tabaci MEAM1 and MED shared 42,77,60 in terms of species, genus, and family, respectively; B. tabaci MEAM1 and MED, inclusively contained totally (non-overlapping) 109,163,116 taxa in terms of species, genus and family, respectively. Compared with the dominant bacteria species in B. tabaci MEAM1, those in B. tabaci MED belonged to genus Pseudomonas such as Pseudomonas mendocina and genus of Rickettisa such as Rickettisa felis, Rickettisa bellii.(2) Populations of the R. bellii-infected and R. bellii-free of B. tabaci had been constructed successfully. We detected the endosymbionts of whiteflies that were collected in China. After five generations of population screening, a stable whitefly population carrying with and transmitting the endosymbiont R. bellii- to subsequent generations was established. Besides, the biotype of the B. tabaci was identified as MED.(3) The effect of R. bellii on history life and development of B. tabaci was evaluated. By mating test, B. tabaci with R. bellii-infected had more reproductive advantages such as shorter developmental time, more offspring, longer survival time and bias female sex ratio than B. tabaci with R. bellii-free. Through ovary dissection, we found that R. bellii-free whitefly had more immature eggs in the initial stage of eclosion. However, in the next day after eclosion, R. bellii-infected whitefly have more advantages in egg development.(4) The copy numbers of bellii gene in different developmental periods of B. tabaci were compared. Quantitative PCR was used to detect the copy numbers of R. bellii gene in DNA samples. The results showed that the copy numbers of R. bellii gene were not significantly different before the pupa stage. However, they had a significantly variation when B. tabaci developed into adult. In the following days, it decreased, while it started a rising trendency in the sixth day after eclosion.Based on metagenomic data, we found the differences of endosymbiont species between the MED and MEAM1, and figured out the dominant endosymbiont. At the same time, we established the stable populations of B. tabaci with R. bellii-infected and R. bellii-free. Furthermore, we investigated the effect of the dominant endosymbiont on the development, survival rate, fecundity, sex ratio of the offsprings of B. tabaci. Our study not only provided a theoretical basis on how endosymbiont affected the reproductive development and diffusion of B. tabaci, but also made the foundation to reveal that how endosymbiont regulated the host to adapt to the environment. |