Cytochrome oxidase II gene 'short fragment' applicability in identification of forensically important insects

Correct insect identification is an important issue in the forensic entomological analysis. Short DNA segments can be used to uniquely identify species. In order to be useful as a forensic tool, a short DNA sequence must be not only easily sequenced, but also contains enough variation to generate unique identifiers at either the species or population levels. In the present study, we assessed the applicability of a 189-bp mitochondrial cytochrome oxidase subunit II (COII) gene fragment in identification. We analyzed 53 specimens representing 14 species belong to Sarcophagidae (Sarcophaga carnaria, Sarcophaga dux, Sarcophaga albiceps, Helicophagella melanura, Phallosphaera gravelyi, Boettcherisca peregrina and Wohlfahrtia nuba), Calliphoridae (Lucilia cuprina, Lucilia sericate, Chrysomya megacephala, Chrysomya rufifacie and Chrysomya albiceps) and Muscidae (Musca domestica and Musca autumnalis). This region was amplified using polymerase chain reaction (PCR) followed by direct sequencing of the amplification products. Nucleotide sequence divergences were calculated using the Kimura two- parameter (K2P) distance model and a neighbour-joining (NJ) phylogenetic tree generated. No intraspecific variation within same species (0%), while interspecific variation ranged from 2% to 25%. All specimens were properly assigned into correct species apart from H. melanura and M. autumalis. Although molecular methods are very useful to identify forensically important insect, we propose to use it only in addition to the conventional methods.