Abstract: 【Aim】 DNA barcoding method was used to identify flea samples from Qinghai Province, western China in order to make up the deficiency of the traditional morphological classification method in this study. 【Methods】 The partial fragments (about 600 bp) of the mtDNA COI gene of 182 flea individuals that belong to 3 superfamilies, 6 families, 22 genera and 44 species were amplified by PCR, sequenced and aligned. The intra-and inter-species genetic distances were calculated with K2P model, and a phylogenetic tree was constructed with the neighbor-joining (NJ) method. 【Results】 Totally 182 COI gene sequences (GenBank accession no.: MG138154-MG138335) were sequenced successfully. The inter-species genetic distance (4%-12%) was significantly greater than the intra-species genetic distance (0.01%-2.90%). The NJ tree obtained showed that samples of the same species formed monophyletic groups with high support value, and inter-species branches were clear. 【Conclusion】 The results confirm that COI gene can be used in molecular identification of fleas.

Key words: COI gene, flea, DNA barcoding, molecular identification, phylogeny, Qinghai