The Species Of Phytoseiid And Phytophagous Mites And The Genetic Diversity Of Three Major Spider Mites In Rubber Plantation

The infestation of phytophagous mites on rubber trees,have become more and more seriousposing an important limited factors for the development of rubber industry in China.In order to provide some basis for the reasonable control of the pest,the speices of phytophagous mites and predatory mites were investigated in rubber plantation in China,and the genetic diversity of different geographical populations of three important rubber mites were analyzed based on COI gene sequencesBased on the morphological and molecular biological identification,5 species of phytophagous mites including Eotetranychus sexmaculatus,Eutetranychus orientalis,Oligonychus biharensis,Panonchus citri Polyphagotarsonemus latuswere found damaging rubber trees in rubber habitat in Hainan,Yunnan and Guangdong,E.Sexmaculatus was the dominant species accounting for 58.8% of the total samples.E.Orientalis and O.Biharensis accounted for 25.1% and 15.9% of the samples respectively.Only a few samples of P.citri were obtained d in some plantations..The predatory mites surveyed mainly belonged to the family Phytoseiidae,which included4 genera and 8 species.Among these 8 species,2 species belonged to the genus Eusuis,1 species belonged to Paraphystoius,1 species belonged to Aesculus and 4species belonged to Amblyseius.Eusuis ovalis is the dominant predator mite,accounting for 32.8% of the total samples,followed by Amblyseius hainensis and eusuius nicholsi,accounting for 21.5% and 22.9%,respectively.Further anlysis found that there were some same species of predator mites and injurious mites in different habitats of rubber.E.ovalis,A.hainanensis,and P.s cracenti were found in rubber trees and their intercropping crops.E.ovalis was the dominant species in rubber trees,intercropping and other plants.E.orientalis was found in both rubber and intercropped crop Alpinia oxyphylla.The dynamics of spider and predatory mites on the rubber trees intercropped with other crops and in ecological rubber plantations were surveyed.The results showed that among the three important spider mites on rubber treesin intercropping and ecological rubber plantations the number of the E.sexmaculatus was the highest.,E.orientalis and O.biharensis were relatively small in population numbers.The population numbers of E.sexmaculatus reached their peak in May or June,and then.fluctuatedand decreased.It was found that the population number of predatory mites reached.the peak in June or July,lagging behind that of E.sexmaculatus,and then the fluctuated and decreased.By comparing spider mites and predator mites in intercroping and ecological rubber plantations,it was found that the fluctuation of population numbers of spider and predator mites iintercropping and ecological was consistent,The population number of spider mites in intercropping rubber plantation was higher than that in ecological rubber plantations,but the number of predator mites in intercroping rubber plantations was lower than that in ecological rubber plantations.In order to establish molecular identification techniques for spider and predator mites in rubber habitats,DNA barcoding was used to identify the mites in rubber habitats.After amplification and sequencing,partial COI gene sequences of 14 mite species were obtained,among which,7 species belonged to family Phytoseiidae,5species belonged to family Tetranychidae,1 species belonged to family Agistemus,1species belonged to family Cunaxidae,All the sequences are 658-680 bp in length,and there were no base insertions or deletions in the sequences of all mites.The average base composition of 14 mites was A(36.3%),T(35.4%),G(14.2%),C(14.1%).The A + T content(71.7%)was higher than G + C content(28.3%).There was obvious base composition bias which was highly consistent with the characteristics of spider mite mitchondrial genes.Itwas proved that the DNA barcoding general primers can be used to amplify mite COI gene.DNA barcoding can be used for molecular identification of mites,and can well distinguish the mites of different families and genera.The ranking of genetic distance between different taxonomic categories is: family > genus > species.The morphological identification results were highly consistent with those of molecular biology.In order to make clear the population genetic variations and genetic diversities of E.sexmaculatus,E.orientalis and O.biharensis,405 individuals of the three mite species were collected from 11 locations in Hainan,Yunnan and Guangdong Province of China and Hanoi of Vietnam.Mitochondrial COI gene sequences were analysed.The haplotypes of the three spider mites are very rich.Among these,both Eutetranychus orientalis have 16 kinds of haplotypes,which are the most.The median-joining network of haplotypes shows that no obvious differentiation is found in Eotetranychus sexmaculatus Riley,while both Eutetranychus orientalis and Oligonychus biharensis Hirst are differentiated into three clusters.The haplotype NJ phylogenetic tree of these three mites also verifies the result,that is: Fst of Eutetranychus orientalis(Fst=0.79193)> Fst of Eotetranychus sexmaculatus Riley(Fst=0.34698)> Fst of Oligonychus biharensis Hirst(Fst=0.12500).The results of genetic diversity of three kinds of spider mites analyzed from different regions are consistent with each other,that is: Yunnan > Hainan > Guangdong.