Search

Entomological material may be used to estimate the time since death occurred (minimum post-mortem interval, mPMI) in forensically obscure cases. The method commonly used to calculate mPMI is the application of a thermal summation model. Little is known about the thermal requirements of Fanniidae. To fill this gap, the influence of temperature on the development time of Fannia canicularis (Linnaeus), a cosmopolitan species with the potential to be used in forensic entomology, was studied. An experiment was performed under nine ambient temperatures. The thermal summation constants (k) and developmental zeros (Tmin) of this species were calculated for six developmental events: hatching, first ecdysis, second ecdysis, wandering, pupariation, and eclosion. Data were primarily analysed with two linear models, and then, since the relationship between temperature and development rate is curvilinear close to the lower and higher developmental thresholds, the relationship was also modelled using three nonlinear models. A fourth nonlinear model was also used to estimate the intrinsic optimum temperature of F. canicularis, at which the population size is maximal and the mortality is the lowest. At 33 °C, larvae did not hatch from eggs, and thus changes in larval body length were analysed at the eight remaining temperatures. Fannia canicularis development from egg to eclosion required a mean ± SE of 481.73 ± 9.89 degree-days above a lower threshold temperature of 4.64 ± 0.19 °C. At the lowest experimental temperature tested, 10 °C, F. canicularis successfully completed all developmental events, although ca. 30% of wandering larvae proceeded to the inactive stage instead of pupariation. Results obtained from nonlinear models were not satisfactory and did not allow us to consider them as reliable from a biological point of view.

In forensic entomology practice, species identification is a prerequisite for any further analysis of collected material. Although morphology-based taxonomy may be hindered by a range of factors, these are not obstacles for a molecular identification approach, so-called DNA barcoding. The Fanniidae are a dipteran family that is attracted to and breeds in decomposing animal carrion and dead human bodies. However, morphological identification of fanniids, both at adult and immature stages, is considered to be difficult, particularly for non-experts. We investigated the usefulness of molecular taxonomy methods as an alternative/supplement for morphology-based identification in European Fanniidae of forensic interest. The material used in this study was collected from various regions in Asia, Europe and North America. We sequenced a barcode region of the mitochondrial cytochrome c oxidase subunit I (COI) in 27 species. For 13 species, including some taxa breeding in dead bodies, this study describes COI sequences for the first time. Our analysis revealed that both mini-barcode and full-length COI barcode sequences give very high specimen identification success. Despite the large number of COI barcode sequences referring to Fanniidae in the BOLD and GenBank databases, previous identification of forensically relevant Fanniidae was hindered by uneven taxonomic sampling. The majority of available sequences refer to species that are not of medico-legal interest, and many species of forensic interest are unrepresented or represented only by a single sequence. Because of erroneous data that are present in depository databases, DNA barcoding must be used with caution and cannot be considered to be the sole alternative to other identification methods. Wolbachia infections in the examined material did not disrupt specimen identification. The obtained results will facilitate precise identification of European Fanniidae of forensic interest, badly preserved material with degraded DNA, as well as matching of unidentified females and immature stages to already described specimens.

We present a forensic case associated with skeletonized human remains found inside a cistern in a coastal town located in the eastern Iberian Peninsula (Valencian Regional Government, Spain). In order to analyse the particular environmental conditions that occurred during oviposition and development of the collected insects, estimated temperatures at the crime scene were calculated by a predictive mathematical model. This model analyses the correlation between the variability of the internal temperature depending on the variability of the external ones. The amplitude of the temperature oscillations inside the tank and the containment of the enclosure is reduced by the presence of water. Such variation occurred within about 2 h due to the time required for heat exchange. The differential equations employed to model differences between outdoor and indoor temperatures were an essential tool which let us estimate the post-mortem interval (PMI) that was carried out by the study of the insect succession and the development time of the collected Diptera specimens under the adjusted temperatures. The presence of live larvae and pupae of Sarcophagidae and empty pupae of Calliphoridae, Sarcophagidae, Fanniidae, Muscidae, Phoridae and Piophilidae and the decomposition stage suggested the possibility that the remains were in the tank at least a year. We highlight the absence of Calliphora and Lucilia spp., and the first occurrence of the phorid Conicera similis in a human cadaver among the entomological evidence. R.L. and J.M.G.V. are thankful for support from MEC of Spain [Grant No. CTQ 2010-19232]. This study was supported by a grant for studies of Phoridae from the Balfour-Browne Trust Fund (University of Cambridge) and Calliphoridae and Sarcophagidae studies by Generalitat Valenciana [GV/2011/039] and Alicante University projects [GRE09-27].

Four experiments, one in each season, were carried out during 2004 in a rural area of Córdoba, central Argentina. Two pigs (Sus scrofa L.), weighing approximately 8 kg each, were used in each of the four experiments. The animals were killed by a sharp blow to the head and immediately placed in an appropriate arthropod trap. One pig was placed in the shade and the other under direct sunlight. This research was conducted to determine the seasonal structure and dynamics of arthropods that constitute the sarcosaprophagous community in a given area of the central region of Argentina. The decomposition process was divided into five stages: fresh, bloated, decay, advanced decay and dry. The duration of each stage varied in different seasons, showing that the temperature and humidity are the most important variables that influence this process. A total of 51,500 adults and 36,909 immature were collected. More than 80% of the specimens collected belong to Insecta, and within this, Diptera were the most abundant order. The flies were mainly represented by adults and immature of the following species: Chrysomya albiceps (Wiedemann) (Calliphoridae), Musca domestica Linnaeus (Muscidae) and Fannia femoralis (Stein) (Fanniidae). Coleoptera were mainly represented by adults and immature of the species Creophilus maxillosus (Linnaeus) (Staphylinidae) and Dermestes maculatus (Geer) (Dermestidae). More than 50% of hymenopteran fauna collected belong to Formicidae. The trophic levels associated with the decomposition of the remains included five categories: necrophagous, parasites and predators of the necrophagous species, omnivores, opportunists and adventives. During faunal succession a strong dominance of the necrophagous species of the family Calliphoridae and Muscidae was observed, mainly during the early stages of decay process in all seasons.

Increasing rates of unsolved homicides in Brazil prompt the need for applied entomological data to be used as a complementary tool by criminal investigators. In that context, we analyzed the occurrence of forensically important insect species (Order Diptera) on 14 cadavers taken into the Institute of Legal Medicine (ILM), in Pernambuco, Brazil, according to the conditions of the body and the pattern of colonisation by insects. Simultaneously, we surveyed the diversity of insects in the surrounding environment using bait traps. Five species were present on cadavers: Chrysomya albiceps, Chrysomya megacephala and Cochliomyia macellaria (Calliphoridae), Oxysarcodexia riograndensis and Ravinia belforti (Sarcophagidae). A total of 4689 adult insects belonging to 24 species of seven dipteran families (Calliphoridae, Sarcophagidae, Muscidae, Fanniidae, Phoridae, Anthomyiidae and Stratiomyidae) was collected at the ILM premises. C. albiceps was the most frequent species on the corpses and the most abundant in the traps. Species referred to as of forensic importance, such as Lucilia eximia, Chrysomya putoria, Oxysarcodexia modesta and Ophyra chalcogaster were collected on traps, but not on cadavers. There seems to be a limited colonisation of cadavers at the scene of the death, despite the ubiquity of necrophagous species in the area. The results contribute to differentiate between species that are involved in decomposition and those found in and around the mortuary installations of the ILM, thus providing potential clues about the locality of death and the post-mortem interval.

Besides the dominant necrophagous dipteran of the families Sarcophagidae and Calliphoridae usually used for post mortem interval (PMI) estimations, species of other families such as Fanniidae have frequently been reported in forensic studies. Though less abundant, these species are prevalent in decomposing carcasses with most reports being anecdotal. In this study we identified adults of the fly family Fanniidae associated to pig carcasses located under different local environmental conditions (sun and shade) in a semiarid area at Mendoza, Argentina during the winter season. We examined the potential of species of this family as indicators of PMI by measuring abundance, time of occurrence and residency time at the carcasses. We identified six species of Fanniidae: Euryomma peregrinum Meigen, Fannia albitarsis Stein, Fannia femoralis Stein, Fannia fusconotata Rondani, Fannia heydenii Wiedemann and Fannia sanihue Dominguez and Aballay. Overall, fly abundance was higher at the sunlit than at the shaded carcass. The most abundant species at the sun was F. fusconotata while at the shaded carcass F. femoralis was the most abundant species. Based on their residency time, however, species with higher potential as PMI indicators seem to be F. heydenii and F. sanihue as their residency time at the carcass was restricted to a short period of the decomposition process. Other species were present throughout most of the decomposition process or in such a low abundance (E. peregrinum) that they were not useful as indicators. These preliminary results indicate that adults of some species of Fanniidae could act as a good complementary indicator species during the winter season. In particular, F. heydenii and F. sanihue should be the focus of further studies which should also expand to other seasons.

A preliminary, systematic field study on the process of decomposition and associated insects was conducted, for the first time, in New Zealand. Using pig carcasses as an animal model for human decomposition, insect colonisation and succession was monitored in three different habitats in the Auckland region where remains are likely to be found. A significant difference in the rates of decomposition was found among the three different habitats of an open field, coastal sand dune area and native bush during the autumn/winter season. The primary colonisers of all carcasses were Calliphora stygia Fabricius (Calliphoridae), Chrysomya rufifacies Macquart (Calliphoridae) and Hydrotaea rostrata Robineau-Desvoidy (Muscidae). Two species were identified as possible representatives of the habitats in which they were found; Fannia sp. (Fanniidae) in the open field habitat and Calliphora hilli Patton (Calliphoridae) in the native bush habitat. Also identified was Sylvicola sp. (Anisopodidae) as a possible indicator of damp habitats as well as a likely indicator of a longer postmortem interval. This preliminary investigation presents a broad outline of the insects associated with remains and the order in which they appear in the Auckland region.