Recovery of human DNA from fly larvae (Order: Diptera) using Powersoil® Pro

Forensic entomology, the use of insects in criminal and civil investigations, is commonly associated with the estimation of the postmortem interval (PMI). Dipteran larvae found on decomposing bodies can be used for PMI estimations, and as a potential source of human DNA to identify individuals and establish scene-to-victim connections. The ability to use fly larvae for multiple purposes would increase their evidentiary value and help investigations. This study investigates the use of DNeasy® Powersoil® Pro (QIAGEN) paired with various forensic genotyping methods to assess the recovery of useful human and fly DNA. Fly larvae were collected at the Southeast Texas Applied Forensic Science (STAFS) Facility from cadavers to process crops and whole fly larvae. Human DNA was quantified using Quantifiler™ Trio (Applied Biosystems™) and short tandem repeat (STR) profiles were recovered with Investigator® 24plex QS (QIAGEN). Human and fly larval mitochondrial DNA were sequenced for HVI and II and CO1, respectively. Genotyping with ForenSeq® MainstAY SE was also attempted to assess the possibility of using next generation sequencing on human DNA recovered from fly larvae. Full and partial STR profiles from crop and whole fly larvae were recovered. Human mtDNA analysis was successful, recovering full sequences and haplogroups for samples that failed STR typing. CO1 sequencing and MainstAY SE yielded additional information for investigative purposes. PMI estimates were provided using species specific development and Total Body Score (TBS). Fly larvae as a source of human DNA can allow laboratories to attempt various genotyping methods on an extract to aid investigations.