Study On Population Genetic Structure And Wolbachia Infection In The Natural Populations Of Spider Mite,Tetranychus Pueraricola

Tetranychus pueraricola is an important economic pest in the Acari.Previous studies indicate that T.pzueraricola,is highly polyphagous.Recently,T.pueraricola was determined to be widely distributed on various plants and in many regions of China.However,the distribution and the population genetic structure of T.pueraricola have not yet been investigated.Molecular markers for studying populations genetic structures include tmicrosatellites,single-copy nuclear genes,mtDNA and so on.Bacterial endosymbionts are tremendously abundant among invertebrates,particularly among arthropods.Wolbachia are endosynbiotic bacteria that live within cells of arthropods and filarial nematodes.In addition to reproduction regulation,Wolbachia also play an important role in their hosts'population genetic variability.There is an increasing evidence that Wolbachia may influence host's evolutionary history and population structure.Therefore,Wolbachia have theoretical and practical significances in evolution of arthropod,and biological control of pest.To better understand the genetic structure of T.pueraricola in China,we investigated the mtDNA variation by sequencing a portion of T.pueraricola.Partial COI sequences were obtained form 397 individuals.Among them,35 polymorphic sites were observed and distinguished 16 different mtDNA haplotypes.Then the Fst values between the populations iin addition to YY-GY population(0.00000),others are all have shown significant differences.Meanwhile,AMOVA results showed that the mite mtDNA-COI is its variation occurred among populations,approximately 85.38%of the total variation,indicating that among its population has a greater degree of variation.In the mean time,we investigated the infection of Wolbachia in 12 natural populations of T.pueraricola by using the wsp sequence data and the MLST data.Our results indicated that the infection rate of Wolbachia ranged from 2.8%to 50%.We detected three Wolbachia strains(wTpuel,wTpue2,and wTpue3),which were unambiguously assigned to supergroup B.We also found double infection of wTpueland wTpue3 in some individuals.In our analysis,we found that wTpuel induced weak CI.However,wTpue3 did not induce CI.wTpuel and wTpue3 were not closely related,therefore we considered the Cl level induced by Wolbachia to be strain-specific.Different Wolbachia strains may have different effects on their hosts' reproductive regulation,therefore,different Wolbachia strains play different roles on hosts' ecology and evolutionary history.Our result indicated the mtDNA Hd and Pi of the infected groups were higher than those of the uninfected groups,it was similar too in single-copy nuclear DNA.The haplotype network systems and AMOVA analyses indicated that the mitochondria less affected by Wolbachia.The study also analyzed the different geographical factors which had influenced on the evolution of T.pueraricola.We found that geography has more effects than Wolbachia infection on population genetic structure in T.pueraricola.