Molecular Analysis of Forensically Important Blow Flies in Thailand

Abstract

Blow flies are the first insect group to colonize on a dead body and thus correct species identification is a crucial step in forensic investigations for estimating the minimum postmortem interval, as developmental times are species-specific. Due to the difficulty of traditional morphology-based identification such as the morphological similarity of closely related species and uncovered taxonomic keys for all developmental stages, DNA-based identification has been increasing in interest, especially in high biodiversity areas such as Thailand. In this study, the effectiveness of long mitochondrial cytochrome <i>c</i> oxidase subunit I and II (<i>COI</i> and <i>COII</i>) sequences (1247 and 635 bp, respectively) in identifying 16 species of forensically relevant blow flies in Thailand (<i>Chrysomya bezziana</i>, <i>Chrysomya chani</i>, <i>Chrysomya megacephala</i>, <i>Chrysomya nigripes</i>, <i>Chrysomya pinguis</i>, <i>Chrysomya rufifacies</i>, <i>Chrysomya thanomthini</i>, <i>Chrysomya villeneuvi</i>, <i>Lucilia cuprina</i>, <i>Lucilia papuensis</i>, <i>Lucilia porphyrina</i>, <i>Lucilia sinensis</i>, <i>Hemipyrellia ligurriens</i>, <i>Hemipyrellia pulchra</i>, <i>Hypopygiopsis infumata</i>, and <i>Hypopygiopsis tumrasvini</i>) was assessed using distance-based (Kimura two-parameter distances based on Best Match, Best Close Match, and All Species Barcodes criteria) and tree-based (grouping taxa by sequence similarity in the neighbor-joining tree) methods. Analyses of the obtained sequence data demonstrated that <i>COI</i> and <i>COII</i> genes were effective markers for accurate species identification of the Thai blow flies. This study has not only demonstrated the genetic diversity of Thai blow flies, but also provided a reliable DNA reference database for further use in forensic entomology within the country and other regions where these species exist.