Molecular Identification Of Pyemotes Based On Mitochondrial CoⅠ And Ribosomal Its2 Gene

Pyemotes are all the insect ectoparasitism mites.The body length is only 200μm. Because there are few morphological features for the classification and identification of the tiny mite and the taxonomy is still imperfect, we have no effective method to make a distinction between the relative species.In recent years, it can resolve the problem using the molecular DNA mark technology.The cytochrome oxidase subunit I (COI) of mitochondrial DNA and internal transcribed spacer 2(ITS2) in 9 populations of Pyemotes were cloned and sequenced.The identification of species and phylogenetic analysis of Pyemotes were studied through the COI and ITS2 gene sequence analysis.The main results are as follows.1.From the sequence analysis of COI gene in 9 populations of Pyemotes, the results showed that the nucleotide sequence length was all 453bp and the base composition was 70.4% A+T average.According to phylogenetic analysis and evolutionary divergence,6 populations of Pyemotes ventricosus group were divided into 3 independent species. The result was consistent with morphological classification and the biology observed result.2.The nucleotide sequences of the COI gene of 9 populations were analyzed and compared, the results showed that the evolutionary divergence was 11.9%-17.1% interspecies and 0-1.3% intraspecies.The No.5 population (SSXD) was closer to Pyemotes Scolyti group than Pyemotes ventricosus group.3.The sequence length of the ITS2 gene of 9 populations was 449-491bp, the evolutionary divergence was 7.0%-17.8% interspecies and 0-0.6% intraspecies. The base composition was 68% A+T average.The result of species identification was consistent with the result of COI.4.Combining the two molecular markers,we could find that COI and ITS2 have successfully identified Pyemotes to species level.