Identification of forensically important sarcophagid flies (Diptera: Sarcophagidae) in China based on COI and period gene.

Unequivocal identification of insect specimens is an essential requirement in forensic entomology. With the development of molecular identification, spate of discussions about the feature of the DNA fragments have been raised. Relying solely on single DNA fragment for delimiting closely related species is supposed to be dangerous. Aiming at obtaining more reliable markers that might be universally used, we explore the utility of 700-bp COI fragment and 678-bp period gene fragment in the identification of Sarcophagidae (Diptera). Thirty-six sarcophagid fly specimens were collected from 19 locations in 11 Chinese provinces. Phylogenetic analysis of the sequenced segments showed that all sarcophagid specimens were properly assigned into nine species with relatively strong supporting values, which indicated the possibility of separation congeneric species with COI and period gene fragments. The difference between intraspecific threshold and interspecific divergence confirmed that the combination of nuclear and mitochondrial genes for species identification is much more accurate. The results of this research will be instrumental for implementation of the Chinese Sarcophagidae database.