A simple molecular method for rapid identification of commercially used Amblyseius and Neoseiulus species (Acari: Phytoseiidae)

Abstract

Predatory mites from the Amblyseius (Neoseiulus) genus (Family Phytoseiidae, Order Parasitiformes) are widely used for protecting plants against pests, especially thrips. The differentiation of Amblyseius and Neoseiulus species by their morphological features is problematic despite the fact that they are taxonomically different genera. The Phytoseiidae family includes a lot of species that are extremely difficult to distinguish from each other. The discovery of new molecular genetic markers might considerably facilitate the express identification of commercial mite species. Despite their high morphological similarity, the three common commercial Amblyseius and Neoseiulus mite species (Neoseiulus cucumeris, Amblyseius swirskii, and Neoseiulus barkeri) differed significantly in the nucleotide sequences of DNA fragments containing the ITS1 and ITS2 internal transcribed spacers. We found that when PCR products of the amplified DNA fragments from A. swirskii, N. cucumeris, and N. barkeri were treated with a combination of AccB1I, AspLEI, and SspI endonucleases and the resulting products were separated by electrophoresis in agarose gel, the obtained picture was sufficiently specific to provide accurate identification of the analyzed mite species. The lengths of the digestion products were different enough to allow their resolution in agarose gels. The PCR-RFLP method developed by us allows the rapid and accurate identification of commercially used Amblyseius and Neoseiulus species without DNA sequencing. The combination of the three endonucleases (AccB1I, AspLEI, and SspI) and FaeI can be used for the differentiation of all other but less frequently commercially used Phytoseiidae mites.