The Morphology And Nucleotide Variation In RDNA ITS-2 Differentiates Psoroptes Isolates From Rabbits And Buffalo

Species of the genus Psoroptes(Acari: Psoroptidae) are astigmatid, communicability, obligatory ectoparasites that cause various forms of psoroptic mange in mammalian hosts including sheep, cattle, goats, horses and rabibits. A wildly used taxonomic key for the genus psoroptes based up on the tradition taxonomic key such as morphology, host and so on divided the psoroptes into Psoroptes cuniculi(P.cuniculi), Psoroptes natalensis(P.netalensis), Psoroptes cervinus(P.cervinus), Psoroptes equi(P.equi) and Psoroptes ovis(P.ovis). Some schooler thought that the P.equi was the first one to be named, so all the psoroptes should be named after P.equi, and doulted the tradition taxonomic key. Then molecular biology method was used in the systematization of the mites.Morphology and molecular biology method were used in this paper to distinguish the P.netalensis and P.cuniculi collected from the body of buffalo and the ear of the domestic rabbit in Sichuan, China. Our study showed that the morphology can not distinguish the other life-cycle mites except the male adult mites: the primary criterion for the species identification were that P.netalensis has a keen opisthosomal lobe, each opisthosomal lobe bearing three long and two shorter leaf-like setae. The base of the setae formed the obsolete lobes; P.cuniculi has a blunt opisthosomal lobe, each opisthosomal lobe bearing two long and three shorter cast setae. The base of the setae foemed the visible lobes.The ITS-2 sequence of P.netalensis and P.cuniculi was amplified successfully(EF025929, EF025930). The molecular biology method results showed that the psoroptic isolated from buffalo exhibited a 89.10% similarity to the psoroptic isolates from rabbits ITS-2. The comparion results showed that the nucleotide sequences homogeneity between the P.netalensis and P.cuniculi was low. The ITS-2 sequence of the P.cuniculi isolates from different host and different geographical regions exhibited a similarity between 95.90-100.00%, and the ITS-2 sequence of P.netalensis isolates from different host and different geographical regions exhibited a similarity between 87.80-89.50%.ITS-2 sequence comparisons and the dendrogram were obtained using the programs DNAstar and MEGA2.0. The molecular phylogenetic trees obtained from four different methods showed that the distance between P.netalensis and P.cuniculi is relatively far. And the bootstrap values of P.netalensis were relatively high(84,98,86,84). P.cuniculi in all molecular phylogenetic trees were aways stay with the other Psoroptes strains, the bootstrap value of P.cuniculi were variance(52,81,84,55). So we confirm the view that the genus P.netalensis and P.cuniculi were much more indicative of a possible different specificity.