Studies On Phylogenetic Relationships Among Some Common Species Of Amblyseiinae (Acari: Phytoseiidae) Based On COI Gene And ITS Gene

This paper aims to analyze the phylogenetic relationships among phytoseiid mites (Acari:Amblyseiinae) in the citrus orchard by comparing partial mitochondrial COI gene sequences of 7 species and ITS gene sequences of 3 species. By using biology software, the genetic structure and gene flow have been analyzed. Finally NJ (neighbor-joining method), MP (maximum parsimony method), ML (maximum likelihood method) molecular systematic trees have been built to disscuss the classification system of phytoseiid mites. The major achievements of this paper are as follows:1. Sequence characteristics of COI gene and phylogenetic relationship of Amblyseiinae based on COI gene.The fragment sequences of COI gene from 7 phytoseiid mites have been analyzed by softwares. Length of COI gene are 453 bp. The average A+T content is 70.2%. obviously biased A+T, it is particularly at codon third position(83.6%). There are 211 variable sites compared with sequences in GenBank. The variability between different species is higher than intraspecies.Aligned with the COI gene of phytoseiid species of citrus orchard from GenBank, NJ, MP and ML trees shows:{[(partial Neoseiulus+partial Amblyseius+ Scapulaseius)+Kampimodromus+Euseius]+(partial Neoseiulus+partial Amblyseius)]}. E. finlandicus and E. ovalis to be sister, Kampimodromus is closer to Neoseiulus and Amblyseius, but the species of Neoseiulus and the species of Amblyseius are confusion in the phylogenetic tree.2. Sequence characteristics of ITS gene and phylogenetic relationship of Amblyseiinae based on ITS gene.The fragment sequences of ITS from 3 phytoseiid mites have been analyzed by softwares. Length of ITS are from 567 to 584 bp. Species from different location are totally the same. The average A+T content is 59.9%. There are 236 variable sites and 72 insertion/deletion in these sequences. Results demonstrated that ITS2 regions are much more conserved than ITS1,5.8S is very conservative with 14 variable sites of 87bp.Aligned with the ITS gene of phytoseiid species of citrus orchard from GenBank, NJ, MP and ML trees shows:{ [(partial Neoseiulus+partial Amblyseius+ Scapulaseius)]+[(Iphiseius+Euseius)+(partial Neoseiulus+partial Amblyseius +Kampimodromus)]}. E. finlandicus,E. nicholsi,E. ovalis and E. concordis to be sister with high bootstrap support, and E. nicholsi is closer to E. ovalis and farther to E. ovalis. Iphiseius seems to be the sister of Euseius, Kampimodromus is closer to Neoseiulus and Amblyseius, also species of Neoseiulus and the species of Amblyseius are confusion in the phylogenetic tree.Compared with NJ, MP and ML trees based on COI gene and ITS gene, the results support the taxonomic status of E. finlandicus,E. nicholsi,E. ovalis and E. concordis, the species of Neoseiulus and the species of Amblyseius are confusion in the phylogenetic tree, The ownership of this two genera are changed more frequent, actually Wu et al. differentiate Neoseiulus and Amblyseius only by the length of a anal awta Z5 in dorsal shield. and show sufficient evidence that Neoseiulus and Amblyseius should not be assigned to two genera, which taxonomic system needs further research.