Abstract: Thirteen Orius species were differentiated using a DNA barcoding technique. Base composition of 59 COI gene fragments were analyzed, intra-and inter-species genetic distances were calculated and phylogenetic trees were established based on neighbor-joining method, maximum parsimony method and bayesian method, respectively. Results showed that base composition of 13 Orius species' COI gene sequence was consistent with the typical insect mitochondrial DNA, A+T average content (66.4%) was higher than G+C average content, A+T content was 90.7% in 3rd position of codon, most base substitutions were synonymous substitutions. Average intra-specific genetic distance was 0.008, average inter-specific genetic distance was 0.128, the two were not overlapped. The results of cluster analysis, based on three different methods, were basically consistent with the results of morphological identification, different individuals of the same population were gathered to a branch in the dendrograms, but there may be a cryptic species of Orius minutus (Linnaeus). The DNA barcoding technique can be potentially used for quick identification of Orius species.

Key words: Orius, DNA barcoding technique, COI gene, genetic distance, phylogenetic tree