title: ITS2 sequences as barcodes for identifying and analyzing spider mites (Acari: Tetranychidae).
abstract: The use of DNA barcodes, short DNA sequences from a standardized region of the genome, has recently been proposed as a tool to facilitate species identification and discovery. Here we show that second internal transcribed spacer of nuclear ribosomal DNA (rDNA-ITS2) barcodes effectively discriminate among 16 species of spider mites (Acari: Tetranychidae) from Israel. The barcode sequences of each species were unambiguously distinguishable from all other species and formed distinct, nonoverlapping monophyletic groups in the maximum-parsimony tree. Sequence divergences were generally much greater between species than within them. Using a 0.02 (2%) threshold for species diagnosis in our data set, 14 out of 16 species recognized by morphological criteria would be accurately identified. The only exceptions involved the low divergence, 0.011-0.015 (1.1-1.5%), between Tetranychus urticae and Tetranychus turkestani, where speciation may have occurred only recently. Still, these species had fixed alternative rDNA-ITS2 variants, with five diagnostic nucleotide substitutions. As a result, we tentatively conclude that rDNA-ITS2 sequence barcodes may serve as an effective tool for the identification of spider mite species and can be applicable as a diagnostic tool for quarantine and other pest management activities and decision-making. We predict that our work, together with similar efforts, will provide in the future the platform for a uniform, accurate, practical and easy-to-use method of spider mite species identification.
authors.affiliation: Department of Entomology, Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Tselila
authors.initials: T
authors.lastname: Ben-David
authors.forename: Sarah
authors.initials: S
authors.lastname: Melamed
authors.forename: Uri
authors.initials: U
authors.lastname: Gerson
authors.forename: Shai
authors.initials: S
authors.lastname: Morin
mesh_terms: D000818:Animals; D021903:DNA, Ribosomal Spacer / Q000737:chemistry* / Q000145:classification; D016678:Genome; D008969:Molecular Sequence Data; D010802:Phylogeny; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA / Q000379:methods*; D040102:Tetranychidae / Q000145:classification* / Q000235:genetics
chemical_list: D021903:DNA, Ribosomal Spacer