Development of Fannia pusio (Diptera: Fanniidae) Under Controlled Temperature Conditions and its Enforcement in the Estimate of the Post-mortem Interval (PMI)

Fannia pusio (Wiedemann, 1830) is a species belonging to the family Fanniidae, which is of great forensic, sanitary, and veterinary interest. The behavioral peculiarities of this species, depending on the temperature at which it is found, may provide additional information for future research. The application of entomology in the forensic field has focused especially on the early colonizing taxa of corpses that are in the initial stage of decomposition. However, species occurring at more advanced stages can contribute to further knowledge, as is the case with F. pusio. In addition, the species has the ability to colonize buried corpses that are inaccessible to larger dipterans. On the other hand, the sanitary and veterinary interest of this species is due to the performance of females as phoretic hosts of Dermatobia hominis eggs that cause myiasis in both animals and humans. In the current study, the behavior of F. pusio was observed at a temperature range of 5°C to 40°C. We found that its viability range is limited between 15°C and 35°C; above and below these temperatures, adults survive but oviposition does not take place. Data collected by statistical analysis were subsequently applied to calculate the post-mortem interval (PMI) using isomorphen and isomegalen diagrams. The results show a directly proportional relationship between growth rate and temperature increase. However, a slowdown in the growth of individuals was observed at extreme temperatures (5°C and 35°C). The results shown in this manuscript, together with the existing bibliography of other species, help to broaden the knowledge of F. pusio, which has not been studied in such depth until now.

Analysis of Microbial Communities: An Emerging Tool in Forensic Sciences

The objective of forensic sciences is to find clues in a crime scene in order to reconstruct the scenario. Classical samples include DNA or fingerprints, but both have inherent limitations and can be uninformative. Another type of sample has emerged recently in the form of the microbiome. Supported by the Human Microbiome Project, the characteristics of the microbial communities provide real potential in forensics. They are highly specific and can be used to differentiate and classify the originating body site of a human biological trace. Skin microbiota is also highly specific and different between individuals, leading to its possibility as an identification tool. By extension, the possibilities of the microbial communities to be deposited on everyday objects has also been explored. Other uses include the determination of the post-mortem interval or the analysis of soil communities. One challenge is that the microbiome changes over time and can be influenced by many environmental and lifestyle factors. This review offers an overview of the main methods and applications to demonstrate the benefit of the microbiome to provide forensically relevant information.

Insect rearing protocols in forensic entomology: Benefits from collective rearing of larvae in a carrion beetle Necrodes littoralis L. (Silphidae)

Forensic entomologists frequently use a developmental method to estimate a post-mortem interval (PMI). Such estimates are based usually on the blow fly larvae or puparia. Data on their development is obtained by rearing them in colonies. In the case of beetles, which can be also useful for PMI estimation, development data is frequently collected by rearing them individually. However, some carrion beetles are gregarious, for instance, Necrodes littoralis (Linnaeus, 1758) (Silphidae). We compared mortality, rate of development and body size of emerged adult beetles reared individually and in aggregations. Mortality was much higher for beetles reared individually, particularly at low temperatures. The rearing protocol affected the time of immature development and the size of adult insects. Individually reared specimens developed much longer at 16°C, whereas at 20°C and 26°C development times of individually reared beetles were slightly shorter. Significant differences in the body size were observed only at 16°C; beetles that developed in aggregations were larger at this temperature. These findings demonstrate that aggregating is particularly beneficial for larvae of N. littoralis at low temperatures, where it largely reduces mortality and facilitates growth. Moreover, these results indicate that in forensic entomology the protocol of individual rearing is unsuitable for gregarious beetles, as it produces reference developmental data of low quality.

Individualised and non-contact post-mortem interval determination of human bodies using visible and thermal 3D imaging

Determining the time since death, i.e., post-mortem interval (PMI), often plays a key role in forensic investigations. The current standard PMI-estimation method empirically correlates rectal temperatures and PMIs, frequently necessitating subjective correction factors. To overcome this, we previously developed a thermodynamic finite-difference (TFD) algorithm, providing a rigorous method to simulate post-mortem temperatures of bodies assuming a straight posture. However, in forensic practice, bodies are often found in non-straight postures, potentially limiting applicability of this algorithm in these cases. Here, we develop an individualised approach, enabling PMI reconstruction for bodies in arbitrary postures, by combining photogrammetry and TFD modelling. Utilising thermal photogrammetry, this approach also represents the first non-contact method for PMI reconstruction. The performed lab and crime scene validations reveal PMI reconstruction accuracies of 0.26 h ± 1.38 h for true PMIs between 2 h and 35 h and total procedural durations of ~15 min. Together, these findings broaden the potential applicability of TFD-based PMI reconstruction.

Life cycle and development rate of Hemipyrellia ligurriens (Wiedemann) (Diptera: Calliphoridae) during monsoon season in South India: applications in estimation of postmortem interval

Hemipyrellia ligurriens, considered as one of the forensically important blow fly species, has a wide distribution in many countries including India. To conduct forensic entomological investigations involving deaths of livestock, human beings and wild animals, standard life cycle data should be prepared for the local blow fly species under various weather conditions. Reliable forensic entomological data specific to geographic locations in India are not available presently to assist the post mortem interval assessment. In this study, life cycle and the rate of development of H.ligurriens was determined during monsoon season in Kerala, South India. Survival rate observed from egg to adult emergence was 44.68 %. Total duration of development of the species from oviposition till adult emergence was 462.57 h. Growth curves based on the age, specific length parameter and time taken for development of each larval stage was constructed. This development model would be helpful for the medical, veterinary and law enforcement officials in forensic estimation of post mortem interval by analyzing the length parameters of larvae collected from decomposed dead bodies of humans, cadavers of wild animals and livestock.