Spider mites are very tiny animals which frequently display morphological variation between populations. Traditional

identification methods take a long time to apply and their key characteristics are difficult to grasp. In order to find a

rapid molecular identification method for the spider mite, Tetranychus truncatus Ehara, Random Amplified Polymorphic DNA

(RAPD) was used to obtain specific bands and the SCAR marker. One prominent and specific fragment of 717 bp was screened and

sequenced (GenBank accession number JF816665) using the OPB04 primer. A pair of SCAR primers (Tt303F and Tt303R)

specific to T. truncatus were designed on the basis of the sequencing results of the 717 bp band. After optimization for the

amplification procedure, these primers were used to successfully obtain a 303 bp band from all developmental stages of T.

truncatus. This band was not found in other related species. The two SCAR primers were also shown to be effective in

monitoring T. truncatus populations collected on eggplant and bean crops in Beijing.