Isolation and detection of ingested DNA from the immature stages of Calliphora dubia (diptera: Calliphoridae) : A forensically important blowfly

Abstract

The forensic entomologist frequently bases time since death (TSD) estimation on fly larvae. In some cases, the food source on which these larvae have completed their development may be questionable, and requires verification to ensure the accuracy of the TSD estimation. Ingested DNA may be isolated from the alimentary canal of immature insects. Previous studies have confirmed the ability to extract ingested DNA from the alimentary tract of third instar blowfly larvae. This study considers the potential to detect ingested DNA from immature stages of the blue-bodied blowfly Calliphora dubia (Macquart) that had fed on sheep liver. Individuals from early first instar larvae through day 3 pupae were surface decontaminated, followed by DNA isolation and detection by amplifying the sheep satellite I region. Fragments of 197 basepairs (bp) and 87 bp were successfully isolated and detected in all stages of immatures until 2-day-old pupae, with detection at this stage being unsuccessful on 3-day-old pupae. This study presents a suitable protocol for the isolation and detection of ingested DNA from immature stages of C. dubia.