Abstract: To solve the problems of identification of sarcosaphagous flies and their larvae and eggs, for which all of eggs and most of larvae could not be identified using their morphological features only, the feasibility of species identification based on a 278 bp region of the gene for cytochrome oxidase subunitⅠ(COⅠ) encoding region of mtDNA was evaluated.Samples were collected on the corpses of rabbits on the grassland in the Chengdu district.The mtDNA of flies was extracted using the improved technique in grinding tissue during extracting DNA from small insects.Reactions were conducted on a Perkin-Elmer 9600 thermal cycler, followed by vertical non-denaturing polyacrylamide electrophoresis.PCR products were purified using the Nucleic Acid Purification Kit.Sequences of both strands were obtained by direct sequence of the double-stranded PCR product using one of the PCR primers and the ABI PRISM Big Dye Terminator Cycle Sequencing Kit. Sequence reactions were electrophoresed on ABI Model 377 DNA Sequencers. A neighbour-joining tree using the Tamura and Nei model of nucleotide substitution was constructed using the MEGA2.1 package. The analysis of a 278 base pairs region of the gene for COⅠencoding region of mtDNA of sarcosaphagous flies collected from Chengdu district showed less than 1% sequence divergence within species and about 10% divergence between species. So it is concluded that this region of the gene for COⅠencoding region of mtDNA of sarcosaphagous flies can be effectively used for identification of them to species level. Owing to the speed, easiness and accuracy of current nucleotide sequencing technology, it is likely to enable the reliable identification of sarcosaphagous flies.

Key words: Sarcosaphagous flies, species identification, mtDNA, COⅠ