DNA-Based Identification of Necrophagous Fly Species Using Abdominal-B (Abd-B) Homeobox Sequence / 대한법의학회지

In medicolegal investigations, correct identification of the necrophagous fly species collected around and on the corpse is an essential step for estimating the postmortem interval (PMI). Therefore, forensic pathologists and entomologists investigating deaths due to violent crimes need a rapid, easy-to-use protocol to identify fly species found on corpses. A rapid and robust DNA-based tool that can distinguish between various immature and mature species from the Calliphoridae, Muscidae, and Sarcophagidae families would be ideal for such investigations. To date, the DNA barcode initiative is the best approach for identifying species-specific nucleotide sequences. We have developed 3 sequence-characterized amplified region (SCAR)-based identification systems derived from the Abdominal-B homeobox sequences of 17 fly species belonging to the Muscidae and Sarcophagidae. The flies used in this study were collected in Korea. These assay systems can classify 17 forensically important fly species into the dipteran family group and reliably distinguish them from inter- and intraspecific fly species through a 2-step multiplex PCR. This novel approach may also be used as an alternative to conventional DNA-based identification methods.

DNA-based Identification of Forensically Important Blow Fly Species in Korea; Aldrichina grahami, Calliphora lata, Calliphora vicina and Phormia regina / 대한법의학회지

Entomological evidence, especially necrophagous flies, are important in estimating postmortem interval in a putrefied corpse. Accurate and rapid species identification of eggs, maggots and pupae is required because growth rates and ecological characteristics are different among different species. But species identification of these immature stages of insects is difficult or impossible to even an expert entomologist. We tried to identify the necrophagous fly species using molecular data. Adult specimens of four forensically important blow fly species [Aldrichina grahami, Calliphora lata, Calliphora vicina and Phormia regina] were used for DNA extraction and sequences analysis of mitochondrial cytochrome oxidase subunit I (CO1) in this study. A total of 560 base pairs(bp) of the CO1 region was recovered using the newly designed specific primer pairs and was sequenced to compare it with those of same fly species registered in NCBI GenBank. The results presented in Table 2 to 6 demonstrate not only the potential utility of the COI sequence in interspecific discrimination, but also indicate that this sequence is probably not suitable for use with intraspecific studies, especially for dividing different local populations within the same species.

Molecular Identification of Six Necrophagous Fly Species (Family: Muscidae) by Mitochondrial Cytochrome Oxidase Subunit I / 대한법의학회지

Estimation of postmortem interval (PMI) in a putrefied corpse has been a long theme in the forensic medicine. Insects, especially necrophagous fly species are now utilized as indicators of PMI because the first visitors to a dead body are usually known to be blow fly species (Family Calliphoridae). House flies (Family Muscidae) are later visitors but they are very significant in forensic entomology because of their worldwide distribution. Entomologic evidences recovered from the scene are often immature individuals such as eggs, maggots and pupae. Because growth rates and ecological characteristics are different among fly species, accurate species identification is essential. As species identification in immature stages is very difficult or even impossible to an expert entomologist, many researchers are trying to identify fly species by molecular techniques. Authors analyzed 400bp of mitochondrial COI gene sequences of six Muscidae fly species (Fannia prisca, Muscina angustifrons, Muscina stabulans, Musca domestica, Hydrotaea dentipes and Ophyra leucostoma). In spite of limited number of flies analyzed in this study, all six fly species have different haplotype of COI gene and shows minimal intraspecific variation. This result shows that six fly species analyzed in this study can be discriminated each other by COI gene sequence analysis. But, more individuals from various geographic region should be analyzed to apply this result to a forensic entomology practice.