Identification of forensically important sarcophagidae (Diptera) by DNA-based method coupled with morphological characteristics

The Sarcophagidae, besides the Calliphoridae, are considered as forensically important insects for investigating postmortem interval (PMI), however, often be neglected. Using decomposing pig bodies with various postmortem intervals, we identified 47 sarcophagid flies from hundreds of fly specimens collected at several Taiwan areas. Species diversity of the sarcophagid flies was further studied based on both morphological identification and DNA analysis at the mitochondrial oxidase subunit I (COI) gene. Seven species, Liopygia crassipalpis, Parasarcophaga misera, P. dux, Liopygia ruficornis, Boettcherisca pergrina, B. formosensis, and Seniorwhitea princeps, were initially identified by microscopic observation. Nineteen of the 47 sarcophagid flies were categorized to be P. dux. The COI DNA sequence variations within intra-species were less than 0.8 % for L. crassipalpis, misera, L. ruficornis, S. princes, B. formosensis, 1.2% for B. pergrina, and 1.8% for P. dux. Our results were consistent to the literature's finding; i.e., DNA variations in intra-species of P. dux were higher than those of other sarcophagid species. Neighbor-Joining tree results revealed that there were three subgroups within the population of P. dux, and the COI DNA sequence of the three was found to be highly variable, but was of high similarity within same subgroup. Morphologically, the 19 P. dux specimens had high similarity, though with minor difference among the three subgroups. The difference was found to locate at pregonite and the color of 2nd genital tergite. The finding of the relationship between DNA sequence variations and morphological features among the intra-species of P. dux was first reported.