Abstract: 【Aim】 Whiteflies belong to a species-rich family with small body size. Identification of whitefly species is commonly done with the aid of molecular methods.  This study aims to clarify the effectiveness of the 5′- and 3′-ends of the mitochondrial cytochrome c oxidase subunit I (COI) gene sequences in molecular identification of common whiteflies species. 【Methods】 The COI gene sequences in 16 whitefly species common in China were amplified using the 5′- and 3′-end universal primers. The obtained 5′-end (641 bp) and 3′-end (738 bp) fragments were sequenced. The intra- and inter-species genetic distances were calculated using the Kimura-2-Parameter model; the phylogenetic trees were established by a neighbor-joining (NJ) method of the MEGA (Version 5.10) software.【Results】 The identification based on the phylogenetic tree was consistent with those based on morphological characteristics for the 16 whitefly species when the 5′-end fragments were analyzed. However, when the 3′-end fragments were analyzed, the identification results based on the phylogenetic tree were not consistent with those based on morphological characteristics in the case of Pealius mori and Bemisia tabaci Asia II 1. The average inter-species genetic distance was 193.1 (0.2897 vs. 0.0015) and 402.4 (0.2817 vs. 0.0007) times higher than the corresponding intra-species genetic distance for the 5′- and 3′-end fragments, respectively. There was no overlap between inter- and intra-species genetic distances when the 5′-end fragments were analyzed, but overlap was observed between P. mori and B. tabaci Asia II 1 when the 3′-end fragments were analyzed. 【Conclusion】 The DNA barcoding based on the 5′-end fragment of the partial COI gene can provide a rapid and accurate identification of these whitefly species.

Key words: Whitefly, COI gene, phylogenetic analysis, genetic distance, species identification, DNA barcoding