Journal of Forensic Entomology

Entomological Specimens Obtained from Human Remains offer a Faster Option for DNA Identification

Alexa Harrod — 2023-01-28

Genetic identification of human remains in advanced stages of decomposition traditionally involves the extraction of DNA from a toenail, bone, or tooth. This extraction protocol typically relies on an overnight incubation and may yield a degraded, unusable DNA profile. Insect life on the remains may provide an equally viable, yet often overlooked means to obtain a DNA profile in a shorter amount of time. This study conducted at the Arkansas State Crime Laboratory (ASCL) examines the possibility of obtaining human DNA from the entomological specimens that accompanied the remains. It also examines the incubation time of the specimens and the class of insects from which a profile could be obtained. Fly and beetle larvae were initially frozen before extraction using the following instruments: Qiagen DNA Investigator Kit in conjunction with the Qiagen EZ1 robotic workstation, Qiagen Quantiplex Pro in conjunction with the Applied Biosystems 7500 Real-Time PCR Instrument, Promega PowerPlex Fusion 6C kit with an Applied Biosystems Veriti Thermal Cycler, and finally an Applied Biosystems 3500xL Genetic Analyzer. Of the fifteen samples of insect life collected, fly larva (Diptera) yielded four usable profiles. The beetle larva (Coleoptera) specimens yielded no usable profiles. Using insect-harvested DNA to identify human remains, in some cases, allows for a faster turnaround time so that remains can be released for mortuary care as quickly as possible.

A reference database for the DNA-based identification of North American Calliphorinae.

Christine Picard — 2023-01-28

DNA-based species identifications continue to be a robust tool for the forensic entomologist to identify immature or damaged specimens. However, much of that identification is dependent on the use of a reliable database that encompasses all species possible. Here, we queried DNA databases for DNA records of COI sequence data of 18 species of Calliphorinae present in North America to determine if the DNA-based identification is reliable, and to provide a resource for other entomologists to use, add to or build off of. Our results indicate that approximately 650bp of the standard DNA barcode is not sufficient to identify all possible species in North America using the DNA, and provide guidance on using this database in future applications.

Forensically important sap beetles (Coleoptera: Nitidulidae) of North America

Lauren Weidner — 2023-01-28

The forensically relevant taxa of the family Nitidulidae (Insecta: Coleoptera) are reviewed and diagnosed. Specifically, two genera were identified as forensically important based on the shared feeding behavior on carrion (Nitidula and Omosita). In total, eight species are reported from North America, including a new country record for Omosita funesta Reitter. Collection records were compiled from 25 major institutions with major holdings from the USA and Canada and used to generate distribution maps for each species. The validity of Omosita nearctica Kirejtshuk was tested with molecular data (COI barcode region), and genetic distances were compared across several representative species for the group. Finally, a dichotomous key is provided for both Nitidula and Omosita at the species level, supplemented with dorsal habitus photographs of each species.

Rearing container size impacts immature development time of Phormia regina (Meigen) (Diptera: Calliphoridae) and time of colonization estimations

Charity Owings — 2022-02-21

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, we 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. We 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, we 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 we 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, we 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.

From Crime Scene to Court: How Should Future Research Address the Current Limitations in Forensic Entomology?

Kate Barnes — 2022-02-21

Over the last 50 years there has been a dramatic increase in the amount of research being conducted in forensic entomology. Given the gravity of the consequences associated with court decisions, it is essential to assess how research in forensic entomology is supporting its practical application in criminal investigations and in court. In this study we employed a questionnaire-based approach, gathering information from professionals from across the world involved in the collection and preparation of forensic entomological evidence, as well as those who present and utilise such evidence in court. This was supported by a bibliometric approach that examined patterns of research publication and collaboration. The questionnaire survey indicated that forensic entomology is predominantly utilised to determine minimum post-mortem intervals. Whilst entomologists are generally confident in their ability to collect, preserve, store, identify and interpret entomological evidence, a number of weaknesses in the application and use of forensic entomology were identified. Additionally, the bibliometric study revealed extensive clustering of research within countries, with relatively little cross-country collaboration. This may result in inhibited flow of research findings, which is likely exacerbated by the low number of appropriate open-access journals. The vast array of factors that may affect insect behaviour, development, community structure and dynamics, as well as sampling reliability, make forensic entomology particularly challenging. Therefore, standardisation of procedures, validation of methodologies and accreditation frameworks will be critical for maximising the utility of practical forensic entomology. Research must underpin the future development of forensic entomology, but it will be most effective with greater levels of collaboration between research teams, and between researchers and practitioners. The global research community will need to be much more coordinated and standardised if it is to achieve its potential in supporting practical applications inside and outside of the court, thereby maximising the societal value of forensic entomology.

From the Editors: JFE Volume 1 (2023)

Adrienne Brundage — 2023-01-28