The Genetic Differentiation,Distribution And Effects On Biological Of Cardinium In Bemisia Tabaci MED

Biological invasion has been an increasingly problem to natural ecosymtem,especially to agroecological system.Bemisia tabaci(Gennadius)is a worldwide superbug and is also a complex species including at least 40 different cryptic species,Among them Mediterranean(MED)and Middle East-Asia Minor 1(MEAM1)are the two mainly invasive species in China.It has been confirmed that B.tabaci harboured variable types of endosymbionts,including primary endosymbiont and seven secondary endosymbionts.Among them,the secondary endosymbiont Caidinium gradually entered the researcher’s perspective as a newly discovered bacteria.Long-term field tests have found that the infection rate of Cardinium bacteria in B.tabaci MED was gradually increasing.Therefore,we began to explore the evolution in the B.tabaci MED in China;the location and copy number changes of Cardinium at different developmental stages in the B.tabaci MED in China;and the effects on the development and biology of B.tabaci MED.The results are as follows:1.In this study,specific primers derived from 16 S rDNA and gyrB genes were used to amplify DNA of Cardinium from 56 populations of B.tabaci MED in China by PCR.The results indicated that the B.tabaci populations in China were widely infected by Cardinium.The 16 s rDNA sequences and gyrB sequences were exactly the same in all positive samples from different regions.Cardinium 16 s rDNA sequences and gyrB sequences in B.tabaci in China were similarity with others belong to Group A,respectively,suggesting that Cardinium in China belong to Group A.The results show that the infection type of Cardinium in the B.tabaci is relatively single.2.Fluorescence in situ hybridization(FISH)was used to identified the localization and distribution of primary symbiotic bacteria(Portiera)and secondary symbiotic bacteria(Hamiltonella and Cardinium)in different developmental stages of B.tabaci MED cryptic species of China.The results showed that threeendosymbionts were carried in different stages.Portiera and Hamiltonella were concentrated in the bacteriocyte.Hamiltonella was encapsulated in the periphery of the bacteriocyte.Cardinium bacteria were concentrated in the bacteriocyte and randomly distributed in the bacteriocyte.Two types of distribution in other parts of the host.3.Quantitative analysis of the copy number of Cardinium bacteria in different developmental stages of host beetle by fluorescence quantitative PCR.The results showed that Cardinium bacteria showed a certain amount of bacteria in the egg stage,which may spread vertically with the mother to the eggs.Then,the amount of bacteria increased,and a small peak appeared at the 1st age,and then fell to the lowest at the 2nd and 3rd ages.In the late 3rd instar,the amount of bacteria increased rapidly,and reached the peak after 3 days of initial emergence.After 7 days of emergence,the amount of bacteria contained was restored,and the amount of bacteria contained in the egg stage was maintained.4.Cardinium has a certain influence on the developmental duration of adult whitefly,but only has significant effects on the 2nd and 3rd instar nymphs.The effect of this bacterium on the adult lifespan and the amount of eggs laid by B.tabaci is not significant.The ratio of females was significantly increased.