Molecular identification of forensically important calliphoridae and sarcophagidae species using ITS2 nucleotide sequences

The application of insect evidence to forensic investigations is mainly based on the estimation of postmortem interval and the identification of insect species from samples that are collected from the crime scene. Due to the limited number of expert taxonomists, species identification is one of the major barriers for crime scene investigators to utilize forensic entomology. Therefore, the molecular identification of species, using mitochondrial cytochrome c oxidase subunit I (COI) gene, has been suggested as an alternative strategy. However, in some cases, these maternally inherited markers cause confusion; hence, nuclear DNA markers such as ITS2 are also required as supporting tools. Eleven Calliphoridae and 5 Sarcophagidae fly species collected from Korea were utilized for PCR amplification and nucleotide sequencing of ITS2 locus. Species Identifier software was used for sequence analysis and comparison. The results demonstrated that 11 Korean Calliphoridae and 5 Korean Sarcophagidae fly species could be distinguished using ITS2 nucleotide sequences. In particular, the sister species, Lucilia illustris and Lucilia caesar were also distinguished, despite the very low level of interspecific diversity. However, when compared with previously reported ITS2 nucleotide sequences, several identification failures were noted. This is the first study that widely analyzed nucleotide sequences of the ITS2 locus from Calliphoridae and Sarcophagidae fly species collected in Korea.