Thermoregulation in P. Terraenovae aggregations, an agent-based approach

International audienceThis paper deals with an important issue of forensic entomology: the estimation of the temperature in a "maggot mass". An agent-based model of the thermoregulation behaviour of fly (Protophormia terraenovae) larvae is described. Simulation results show that the model reproduces an important observed pattern and thus, might be used in entomological expertises

Quantifying the Temperature of Maggot Masses and its Relationship to Decomposition

Numerous Calliphoridae species have been observed to form larval aggregations during the feeding stage of development, resulting in localized increases in temperature. This study investigates the relationship between maggot numbers in a mass and heat generation. Single-species aggregations (Lucilia sericata) of various sizes (50–2500 individuals) were reared in the laboratory at a constant ambient temperature of 22°C. Internal mass temperatures were recorded every 5 min throughout the feeding stage of development. Results showed that mass temperatures increased with mass numbers (p-value < 0.001), ranging from 2.5 to 14°C above ambient. A minimum mass size of 1200 produced overall temperatures that were significantly warmer than ambient, diverging away from 22°C after c. 26 h. These results indicate that the microclimate of a mass has the potential to differ significantly from ambient, which may be influencing larval development rates and should therefore be factored into mPMI estimates to increase accuracy

Mixed-species aggregations in arthropods

This review offers the first synthesis of the research on mixed-species groupings of arthropods and highlights the behavioural and evolutionary questions raised by such behaviour. Mixed-species groups are commonly found in mammals and birds. Such groups are also observed in a large range of arthropod taxa independent of their level of sociality. Several examples are presented to highlight the mechanisms underlying such groupings, particularly the evidence for phylogenetic proximity between members that promotes cross-species recognition. The advantages offered by such aggregates are described and discussed. These advantages can be attributed to the increase in group size and could be identical to those of non-mixed groupings, but competition-cooperation dynamics might also be involved, and such effects may differ between homo- and heterospecific groups. We discuss three extreme cases of interspecific recognition that are likely involved in mixed-species groups as vectors for cross-species aggregation: tolerance behaviour between two social species, one-way mechanism in which one species is attractive to others and two-way mechanism of mutual attraction. As shown in this review, the study of mixed-species groups offers biologists an interesting way to explore the frontiers of cooperation-competition, including the process of sympatric speciation.PostprintPeer reviewe

A Biological and Procedural Review of Forensically Significant Dermestes Species (Coleoptera: Dermestidae)

The analyses of the insect species found on decomposing remains may provide useful information for the estimation of the minimum time elapsed since death and other parameters, such as causes and circumstances of death. The majority of research has focused on the early colonizing species, typically blowflies, while research concerning late colonizing insects is currently sparse. Dermestid beetles of the genus Dermestes L. (Coleoptera: Dermestidae) are one of the predominant insect species associated with decomposing remains during dry decay and skeletal stages of decomposition. In some dry environments, Dermestes species are likely to be the only necrophagous insects feeding on the decomposing remains. Furthermore, Dermestes species (immature and adults), their remains (cast skins and fecal material), and their artifacts (pupal chambers) are frequently found associated with ancient remains (e.g., mummies, fossils). Dermestes species have a worldwide distribution and are considered important in decomposition processes, forensic investigations, and economically as a known pest of stored products. Despite their recognized forensic importance, there is limited data documenting the ecology, biology, and the growth rates of the forensically relevant species. The aim of this review is to provide a comprehensive synopsis on the available literature concerning Dermestes species associated with forensic cases. In particular, aspects of colonization behavior, growth rates for forensic taxa and potential best practice guidelines for forensic casework encompassing late colonizing Dermestes species are discussed

Use of necrophagous insects as evidence of cadaver relocation: myth or reality?

The use of insects as indicators of postmortem displacement is discussed in many text, courses and TV shows, and several studies addressing this issue have been published. However, the concept is widely cited but poorly understood, and only a few forensic cases have successfully applied such a method. Surprisingly, this question has never be taken into account entirely as a cross-disciplinary theme. The use of necrophagous insects as evidence of cadaver relocation actually involves a wide range of data on their biology: distribution areas, microhabitats, phenology, behavioral ecology and molecular analysis are among the research areas linked to this problem. This article reviews for the first time the current knowledge on these questions and analysze the possibilities/limitations of each method to evaluate their feasibility. This analysis reveals numerous weaknesses and mistaken beliefs but also many concrete possibilities and research opportunities. 55 Previous reviews have gathered and explained the aims and methods of forensic entomology (11, 56 28, 35, 154), but some fundamental questions remain unresolved, particularly the potential to use 57 insects as evidence of corpse relocation. 58 Forensic taphonomy can include a variety of changes due to human activity, especially 59 steps taken to hide a cadaver (77). Attempts to prevent discovery often include cadaver 60 concealment, wrapping and displacement. Such post-mortem relocation can occur shortly after 61 death or after days of concealment and can take place over a short distance (e.g., from the room 62 where the death occurred to the garden of the house) or a longer distance. In most cases, the 63 environment where the cadaver was hidden is very different from that of the place where death 64 occurred (137). Forensic entomology manuals and courses often state that insects can be used as 65 evidence of cadaver relocation (9, 28, 35, 89, 117, 126, 144) because the biology and ecology of 66 necrophagous species can convey information on where and how insects live and thus may 67 highlight inconsistencies regarding cadaver location and decomposition. However, while this idea 68 is appealing, it may not reflect reality. It may seem obvious that &quot;if a body is discovered with insects restricted to a habitat or 71 geographic region different from that in which it is discovered, this is an indication that the body 72 may have been moved following death&quot; (117). However, most, if not all, European necrophagous 73 species have large distribution areas covering many countries and hundreds of thousands of square 74 kilometers, making the sampling of non-native species quite unlikely. While each species has an 75 ecological niche (e.g., forest or synanthropic; sun or shady habitats), such preferences are not rules. 76 Additionally, as some species can travel kilometers to find carrion, microhabitats are only relative 77 concepts (22, 118). The long dispersal capability of most necrophagous species, especially 78 blowflies, makes it difficult to relate a given species to a particular place or habitat and thus draw 79 inferences regarding cadaver relocation (166). 80 Temporal separation is another characteristic of necrophagous species. The phenology 81 (cyclic and seasonal phenomena) of blowflies is well known; some species are primarily active 82 during hot weather, while others are well adapted to cold climates (157). Such seasonality could, 83 under certain circumstances, contribute useful information regarding the chronology of cadaver 84 decomposition. However, the presence of larvae of a summer species on a winter cadaver does not 85 constitute indisputable evidence of cadaver relocation. Colonization time is also strongly 86 dependent of the stage of decomposition. Although it is far more complex than chronological 87 succession (94), succession on cadavers has been experimentally shown in several countries and 88 under multiple conditions (1, 3, 5, 8). Divergence from known succession patterns such as the 89 absence of certain species or unusual associations might indicate cadaver relocation or 90 concealment. The presence or absence of some instars is also of great interest, especially with 91 regard to wandering larvae or pupae of pioneer species (e.g., Calliphoridae flies), which pupate 92 away from the cadaver and can thus be found after cadaver removal. 93 Advances in genetics also offer numerous opportunities. First, genetics make it possible to 94 connect individuals to a local population or even sub-population. As noted by Tomberlin et al., 95 such possibilities are of great interest in the context of cadaver relocation (154). More anecdotally, 96 the genetic analysis of gut content has interesting potential to indicate which cadaver larvae have 97 been feeding on (32, 34). This technique should be developed in the coming years and provide 98 new tools for forensic entomologists and crime scene investigations. 99 This article reviews the current knowledge and promise of each method and evaluates its 100 feasibility. This analysis reveals the weaknesses and mistaken beliefs regarding the use of forensic 101 entomology as evidence of cadaver displacement as well as many concrete possibilities and 102 development opportunities. 104 A.2 Survey methodology 105 The first phase of this survey was the identification of the the magnitude of this problem. 106 This step was addressed by searching in the main forensic entomology manual published in 107 English since these last 40 years if the question of corpse relocation was afforded. We found 108 references to this idea in most of them (9, 28, 35, 89, 117, 126, 144), but only a few case reports 109 (17, 67, 91). On the other side, we found several research article addressing this question as a main 110 goal or claiming it a potential application of their findings. Accordingly, use of insects to infer 111 corpse relocation appears being a complex and unstructured problem with numerous and disparate 112 information that deserved to be reviewed. 113 We first searched for the books and publication clearly addressing this question. From this 114 dataset, we listed the various facets of the problem and gathered them into four main concept: 115 spatial separation, behavior / development, phenology / colonization time and molecular analyses). 116 We then searched in the literature specific to each of these fields for data of potential use. This 117 datased was then analyzed to highlight discrepancies or spot methods with true potential 118 application. Spatial separation 122 Only a few insect species are associated with cadavers, and even fewer are strictly 123 necrophagous (requiring a cadaver to feed on during at least a part of their development) (144). 124 Their diversity is visible in the variability in insect size, shape, behavior, ecological niche and 125 distribution and reflects species-specific adaptations, which allow species to exploit different 126 habitats and resources. Johnson defined four orders of habitat selection, from large geographical 127 areas to local microhabitats (87). Furthermore, Matuszewski et al. defined species indicators of 128 cadaver relocation as those that at least 1) have a strong preference for a given geographical area 129 or habitat, 2) are resistant to relocation disturbance, 3) live on cadavers and 4) colonize cadavers 130 shortly after death (112). Common species are also more likely to be found in association with 131 criminal cases than are rare species. Unfortunately, the association with habitat appears to be more 132 pronounced in the less common species than in those that are more common (99)

Ils peuplent les morts : approche entomologique médico-légale

National audienc

Insectes nécrophages

National audienc

Les retables des Alpes de Piémont-Savoie aux XVIIe et XVIIIe siècles

Entre le XVIIe et le XVIIIe siècles, un art religieux spécifique se développa dans les régions de montagne du duché puis royaume de Piémont-Savoie, donnant naissance à une multitude de retables. L’étude de cette production, qui s’épanouit, entre France et Italie, dans les limites d’un Etat placé par l’histoire et la géographie au carrefour de toutes les influences traversant l’Europe moderne, présente un intérêt qui dépasse très largement sa région d’origine. L’incontestable originalité de l’art religieux alpin procède d’abord de la géographie, de l’histoire et de la culture locale. Cet art s’insère en même temps dans le vaste mouvement baroque qui s’épanouit dans toute la sphère d’influence de la Contre-Réforme catholique, touchée par les prescriptions du Concile de Trente. Sur la base d’un corpus de près de cinq cent retables, répartis dans neuf vallées alpines, la Valsesia, le Val d’Aoste, le Val de Suse, la Maurienne, la Tarentaise, le Beaufortain, le Faucigny, le Chablais et le Genevois, cette étude vise à comprendre les tenants et les aboutissants du processus créatif qui présida à la naissance de ces œuvres. L’étude des prix-faits, documents clés de la commande, conduit à souligner le rôle majeur des communautés paroissiales, représentées par les communiers, sans toutefois omettre celui, peut-être moins évident, des pouvoirs spirituels et temporels, ni surtout celui des « gens de métier ». Ces derniers, sculpteurs, peintres et doreurs, surent réaliser la synthèse entre les volontés villageoises, les exigences religieuses et leurs propres aspirations esthétiques. Cette production artistique résulte donc d’un équilibre des pouvoirs propre à ces régions.Between 17th and 18th centuries, a specific religious kind of art developed in the Duchy (later a Kingdom) of Piedmont-Savoy’s mountainous regions and resulted in a large number of altarpieces. The study of this production, which blossomed between France and Italy, within the borders of a state that history and geography made a converging point of all the influences crossing modern Europe, is of great interest even beyond the region it came from. The indisputable originality of alpine religious art first proceeds from geography, history and local culture. However, this art is part of the vast baroque movement that blossomed throughout the sphere of influence of the Counter-Reformation, i.e. in the regions where the Council of Trent’s prescriptions actually applied. Based on a corpus of almost five hundred altarpieces spread out in nine alpine valleys (Valsesia, Valle d’Aosta, Valle di Susa, Maurienne, Tarentaise, Beaufortain, Chablais and Genevois), this study aims at understanding the ins and outs of the creation process that led to the birth of those works. The study of the "prix-faits" (contracts), regarded as key documents for any order, leads to emphasize the major part played by the "communiers", who were landowners representing parish communities, yet without omitting either the perhaps less evident part played by spiritual and temporal authorities and, above all, by "professionals". The latter, sculptors, painters and gilders, succeeded in producing a synthesis between villagers’ will, religious requirements and their own aesthetic yearnings. So, this artistic production ensues from a balance of powers quite peculiar to those regions