D3009: COI DNA barcoding of forensically relevant insects collected during decomposition in Huntsville, Texas, USA

Forensic entomology is a vital tool for estimating the postmortem interval (PMI) or time since death. Insect succession, which considers the order of insect colonization, is one of the methods employed for PMI estimation. However, to ensure accurate PMI estimations based on insect succession, data must be recorded that shows the insects present. Since the diversity of insects varies by location, successional data is also specific to the region where the research is conducted. Accurate species identification is crucial for succession based estimations, which is commonly achieved through morphological identification. However, challenges such as experience of the entomologist, availability of identification keys, and life stages, such as Dipteran larvae, can arise. DNA barcoding can help overcome these challenges by sequencing insects’ DNA. The mitochondrial cytochrome oxidase 1 (COI) gene is commonly used for insect DNA barcoding. This study collected insects from various cadavers between 2009 and 2010 at the Southeast Texas Applied Forensic Science (STAFS) Facility. The insects were identified to the species level, and successional data was recorded. Insects from the orders Diptera and Coleoptera were sampled for DNA barcoding, and the sequences underwent a BLAST search for species identification. The study found highly similar sequences to those available in databases, indicating an accurate identification. Some novel polymorphisms were found, and sequences from insects that had no previous entry in GenBank were recovered. This study highlights the importance of DNA barcoding in forensic entomology and its potential to improve successional data accuracy in PMI estimation.