The Molecular Phylogeography Of Cheyletus Malaccensis(Acari:Cheyletidae)Based On Mitochondrial COI And 12S RRNA Sequence Data

Cheyletus malaccensis(Oudemans)(Acari:Cheyletidae),is a predatory mite widely distributed in nature as well as in agriculture fields and storages.It has important economic values,because of control pest mites,such as spider mites and gall mites.In this study,C.malaccensis collected from 11 provinces.Mitochondrial COI and 12S rRNA sequence as molecular markers to analyed the phylogeographic structure of C.malaccensis in China.In this study,we discussed the factors which affecting the geographical structure of C.malaccensis and procide a theoretical basis for the prevention and treatment of stored grain mites.The main conclusions are as follows:(1)There is a obvious bias of A+T in COI sequences(709 bp)and 12S rRNA sequences(390 bp)of all the C.malaccensis in our study.It all got high haplotype diversity(Hd)in COI and 12S rRNA with 0.9405 and 0.8924,respectively.It got high nucleotide diversity(pi)with 0.01959 and 0.10457,too.In general,there is a high genetic diversity in all sampled populations.(2)There are three branches in the haplotype phylogenetic tree and haplotype network of COI sequence,two in 12S rRNA sequence’s.In the three clades of COI sequences:the A clade has 157 individuals which included 32 populations with 24 haplotypes;the B clade has 78 individuals which contained 30 populations with 23 haplotypes;the C clade has 21 individuals which represented only 7 populations with 3 haplotypes.In the two clades of 12S rRNA sequences:the A clade has 43 individuals which included 19 populations with 4 haplotypes and the B clade has 54 individuals which contained 21 populations with 5 haplotypes.There is not a clear correlation between the distribution of haplotypes in the haplotype network and geographical distribution.Phylogenetic tree of individuals showed the same results.(3)Tajima’s test and Fu’ FS test of the COI and 12S rRNA molecular markers showed that there is not occur the population expansion phenomenon in most geographic populations.The AMOVA showed a significant differentiation between haplotype phylogenetic clades,and a smaller between populations.Spatial structure analysis of two sequences showed no significant correlation between genetic and geographical distance.All of these results have shown that the C.malaccensis has no significant system geographical structure.Since the Quaternary glacial,dramatic changes in climate and geographical environment takes the difference between habitats,produced a significant genetic differentiation between populations in different geographic regions which led to a clear genetic structure in the phylogenetic tree.But the grain production and trade activities of human promoting gene flow between populations of different geographical regions,the previous system geographic structure is changed in a short time,thus forming the current Individual phylogenetic structure in which different geographic populations of individuals are staggered.So,the C.malaccensis might be due to both long period of natural history and recent human disturbance to formation the geographical structure obtained in this study.