Technical note: A technique to mount Sarcophagidae and Calliphoridae (Diptera) larvae for forensic identification using geometric morphometrics

Geometric morphometric analyses use landmark coordinates from images of specific areas on specimens. Therefore, to minimize differences arising from human preparation, preparation of the specimen is crucial. The application of geometric morphometrics has been used in entomology for identifying adult dipteran species, however, applying this technique to larval specimens requires the production of standard protocols which would allow specimens to be compared equally. This proposed protocol consists of a two-step process:

1. using 15% potassium hydroxide (KOH) to clear the specimen, followed by rinsing the specimen with 80% ethanol;

2. removal and spreading of the mouthhooks on a slide for imaging and analysis.

The goal of this work is to standardize specimen preparation, which would reduce human error and facilitate use of geometric morphometrics to identify dipteran larvae.

Analysis of Alternative Food Sources for Rearing Entomological Evidence

Forensic entomology is a well-established tool for evaluating the death, or abuse, of a person. Insect evidence provides valuable information as related to time of colonization and movement of remains from one location to another. Blow flies (Diptera: Calliphoridae) are commonly found on human remains throughout most stages of decomposition, and when entomological evidence is collected these taxa tend to be the most numerous. However, very few crime laboratories across the country have collection and rearing protocols for these forensically important insects. A lack of knowledge in collection techniques and limited access to an appropriate food source are the main reasons for absence in adequate collection and rearing protocols. Thus, when crime scene investigators or pathologists collect insects, they are often mishandled (e.g., placed into containers with no air holes, no food, or a food source that is not sustainable for their development). To address this issue, we analyzed easily accessible and cost-efficient alternative food sources for blow flies; specifically, tuna and wet cat food compared to beef liver (control). Survivorship and development were examined for each food source using the blow flies Phormia regina (Meigen) (Diptera: Calliphoridae) and Cochliomyia macellaria (Fabricus) (Diptera: Calliphoridae). These findings provide an overview of possible alternatives that could be used as a sustainable food source in crime laboratories when immediate action from a forensic entomologist cannot be obtained.

An Analysis of Forensically Important Insects Associated with Human Remains in Indiana, U.S.A

Research documenting insect colonization of human remains is limited in North America, and currently nonexistent for the American Midwest. Such research is essential for forensic entomologists to identify species of research interest in a region. In this study, we collected insects from human remains in 24 cases across Indiana from June 2016 through September 2018. We analyzed species composition across scene type and season. Eight species of blow flies were collected as larvae from human remains, with Phormia regina and Lucilia sericata as the two predominant colonizers. Phormia regina was the most numerous species collected from outdoor scenes (73.6% of total collections) while L. sericata was the most numerous from the indoor scenes (60.4% of total collections). With scene types pooled, Calliphora vicina and Cochliomya macellaria were the predominant species in the fall (55.6% and 42.2%, respectively); P. regina was the dominant colonizer in the spring (68.6%); and P. regina and L. sericata were the predominant colonizers (46.5% and 44.4%, respectively) in the summer. In addition to these findings, we confirmed the first record of Lucilia cuprina colonizing human remains in Indiana having collected this species from three cases. A single adult Chrysomya megacephala was collected from an indoor scene in southern Indiana, which represents its second collection in the state. Beetles belonging to the families Staphylinidae, Silphidae, Histeridae, Cleridae, Trogidae, Dermestdae, and Nitidulidae were also collected from two outdoor scenes. This study provides important baseline data for forensic entomologists in Indiana, as well as surrounding states with similar environments.