Analysis of 28S rRNA and COⅠ Gene Sequence of Nine Necrophagous Calliphorid Flies from Luoyang

Objective To assess the feasibility of using 28S ribosomal RNA （28S rRNA） and mitochondrial cytochrome c oxidase subunit Ⅰ （COⅠ） gene sequences of nine necrophagous Calliphorid flies for the identification of common necrophagous Calliphorid flies, and to provide technical support for postmortem interval （PMI） estimation. Methods Twenty-three Calliphorid flies were collected and identified morphologically, and DNA were extracted from legs. The gene fragments of 28S rRNA and COⅠ were amplified and sequenced, then the sequence alignment was performed with BLAST. The composition of obtained sequences was analyzed and evolutionary divergence rate between species and intraspecies were established. The phylogeny tree was constructed with neighbor-joining method. Results The 23 necrophagous Calliphorid flies were identified to 9 species of 5 genera. The 715 bp from 28S rRNA and 637 bp from COⅠ gene were obtained and the online BLAST result showed more than 99% of similarity. The phylogeny tree showed that the necrophagous flies could cluster well into 9 groups, which was consistent with morphological identification results. The intraspecific difference in 28S rRNA was 0 and the interspecific difference was 0.001-0.033. The intraspecific difference in COⅠ was 0-0.008 and the interspecific difference was 0.006-0.101. Conclusion Combined use of 28S rRNA and COⅠ gene sequence fragments can effectively identify the nine Calliphorid flies in this study. However, for closely related blowfly species, more genetic markers should be explored and used in combination in future.