This article presents research into the development rate of blow fly larva and time of colonization as measures used by forensic entomologists to investigate human remains.
Development rate is the primary biological parameter used by forensic entomologists to estimate the time of colonization (TOC). As such, the importance of quantifying the effects of intrinsic and extrinsic factors on development rate, as well as their impact on TOC estimations, cannot be understated. Here, the authors examined the impact of a potentially important, yet overlooked, component of development study design (rearing container size) on immature development time of the black blow fly, Phormia regina (Meigen). To test this, first instar P. regina larvae were arbitrarily assigned to one of three container sizes (small, medium, and large) and were observed every 24 h for the post-feeding stage, pupation, and adult eclosion. The authors observed significantly shorter larval development times (P < 0.003) and significantly longer pupal development times (P < 0.001) in large containers compared to medium and small containers. Furthermore, the authors used the data generated from our study along with four additional published developmental studies for P. regina to estimate the TOC of four sets of human remains at the Anthropology Research Facility at the University of Tennessee. Our data from all container sizes produced accurate estimations for Donors 1, 3, and 4, while the authors obtained accurate estimations only from the small treatment for Donor 2. The published datasets for P. regina examined here each produced accurate estimation ranges for at least 3 of 4 human donors. Overall, the authors showed that rearing container size significantly impacts attributes of blow fly development, and that this has the potential to impact the accuracy of TOC estimations with human remains. (Published Abstract Provided)