Necrophagous Insects Research Articles

Initial laboratory validation of temperature development models for Necrodes littoralis L. (Staphylinidae: Silphinae)

Development models of necrophagous insects are applied in forensic entomology for post-mortem interval estimation. Such estimates may be used as scientific evidence in legal investigations. For this reason, it is important that the models are valid and that the expert witness is aware of their limitations. Necrodes littoralis L. (Staphylinidae: Silphinae) is a necrophagous beetle species that frequently colonizes human cadavers. Temperature models of development for the Central European population of these beetles were recently published. In this article, we present results of the laboratory validation study for these models. Errors of beetle age estimation differed significantly between the models. Thermal summation models yielded the most accurate estimates, and the isomegalen diagram least accurate estimates. Errors of the beetle age estimation varied across beetle developmental stages and rearing temperatures. In general, most development models of N. littoralis were satisfactorily accurate in estimating beetle age under laboratory conditions; therefore, the study provides initial evidence to support their validity in forensic cases.

Case closed – Wrappings and encasement delays and reduces fly presence on body parts

Homicide, particularly where a body has been concealed, is uniquely challenging for investigators to estimate the time of occurrence due to the methods employed by perpetrators to hide the body or its constituent parts from detection. The regularity of necrophagous insect lifecycles to determine minimum post-mortem interval (minPMI) is widely employed but remains an unreliable technique if used without a clear understanding of the factors that affect insect access and oviposition behaviour to concealed remains.The purpose of this study was to investigate the effect of wrapping body parts on fly colonisation and implications for minPMI calculations. Field studies were carried out using four treatments of pork (as surrogate body parts), in five replicates, one unwrapped, the other three wrapped in either a black plastic sack, a small-zipped wash bag (to simulate a suitcase), or a plastic sack further placed in a wash bag. Over a 48-h period all the methods of wrapping significantly disrupted the host-finding process of blowflies to dismembered carcasses, with a delay of initial contact and oviposition of 30+h (dependant on wrapping) and even more in wet conditions (48+ h). Egg numbers were also reduced by as much as 99.1% on wrapped samples compared to unwrapped. These new findings highlight the importance of applying adjustments to minPMI calculations when encountering wrapped remains. Advances in the accuracy of minPMI calculations will prevent the waste of valuable police time and resources and better focus the search for witnesses and suspects in homicide investigations.

A Preliminary Study of Body Decomposition and Arthropod Succession in an Arid Area in Northwest China During Summer.

The study of insect fauna and their development and succession patterns on decaying cadavers is crucial to promoting insect evidence as a useful tool in forensic science, particularly for estimating the postmortem interval (PMI). Body decomposition and arthropod succession are affected by many factors and exhibit substantial regional variations; therefore, detailed succession studies in different biogeographic regions are required for understanding the successional patterns of insects in various environments. This study was conducted in the summer of 2021 using three domestic pig carcasses (Sus scrofa domestica L., 1758) in the field of Shizuishan City, Ningxia, Northwest China. A total of 40 species of necrophagous insects belonging to three orders and 16 families were collected. Among Diptera, Lucilia sericata (Meigen,1826), Chrysomya megacephala (Fabricius,1794), and Phormia regina (Meigen,1826) (Diptera: Calliphoridae) were the dominant species. As for Coleoptera, the dominant species changed throughout the process of carcass decomposition from Saprinus semipunctatus (Fabricius,1792) (Coleoptera: Histeridae) to Dermestes maculatus DeGeer,1774 and Dermestes frischii Kugelann,1792 (Coleoptera: Dermestidae). The carcasses desiccated rapidly and reached the remains stage under extreme conditions of high temperatures and low humidity, after which a large amount of dried tissue of the carcasses attracted populations of Coleoptera, particularly Dermstidae, which were abundant and remained until the end of the experiment on day 50. The current study is the first forensic entomological investigation of succession in Northwest China and provides basic data for the estimation of PMI during summer in this region.

Preliminary Study on the Larval Development of Calliphora vicina (Diptera: Calliphoridae) on Different Types of Substrates Used as Reference in Forensic Entomology

Necrophagous insects are indicators of corpse decay. Analyses of their development stages give us indications on the degree of decay of corpses and contribute to the determination of the post-mortem interval. The differences in structure, biochemical composition and nutritive capacity of the cadaveric substratum can impair the duration of the developmental stages and dimensions of the organisms that metamorphose. This work tackles the study of the development, in laboratory conditions, of Calliphora vicina in correlation with different nutritive substrates (from areas of the corpse strongly affected by the incipient attack of Diptera) in order to obtain preliminary data, aiming to determine the post-mortem interval.

Identification of Forensically Important Carrion Beetles (Coleoptera: Staphilinidae) in China Based on COI and COII.

Unambiguous and speedy necrophagous insect species identification is common task in forensic entomological study. Carrion beetles (Staphilinidae: Silphinae) belong to a small group of Coleoptera with less than 200 species worldwide. Some species are commonly found on dead body during forensic entomological investigation. Despite some species are hard to be categorized morphologically, present DNA-based technologies offer a potential identification strategy. Here, 37 carrion beetle specimens were collected from 15 locations throughout Chinese mainland. The cytochrome oxidase subunit I (COI) and II (COII) genes among all specimens were successfully sequenced, which provided reliable markers for precise identification. Mostly, the interspecific distance could clarify the capability of these genes for identifying included carrion beetle species. Exceptions existed between close species in Nicrophorus genus (Fabricius 1775). The sequenced gene's phylogenetic analysis revealed that all carrion beetle specimens were correctly classified into eight genera, and most have relatively high supporting values (>90%). Our data gives genetic diversity and a reference for global forensically important carrion beetle species identification, as well as a conductive significance for future application of Chinese carrion beetles in forensic entomology.

Forensic Entomotoxicology: A Brief Look at Sample Preparation Techniques – A Review

Forensic entomotoxicology is a relatively new science whose applications aims the detection of toxic substances through a matrix of necrophagous insects in a crime scene. In addition, it aims the investigation of the impacts of the xenobiotics on these insects, generating impacts in the measurement of the post-mortem interval (PMI). Calliphoridae larvae, the most important insect for forensic entomology, has an average amount of 25% of crude fat and 53% of crude protein, being a complex matrix that requires some sample preparation methodology before inserting the sample in some equipment to perform the chemical instrumental analysis. Sample preparation methods should be applied in order to increase the protection of analytical equipment from impurities present in the arthropod matrix, as well as increase the detectability of the test analyte by the analytical instrumentation of choice. Thus, the objective of the present work is to compile sample preparation techniques since traditional procedures until new approaches found in the scientific literature applied for entomotoxicological analysis in Calliphoridae specimens and respective analytes. It was observed the lack of a complete standardization for entomotoxicological approach, mainly for traditional extractions preparations. In this sense, microextraction-based techniques become an even greater challenge for arthropod–like matrix, especially in specimens from Calliphoridae family for xenobiotics determination. So, the development of sample preparation techniques with more sustainable approaches, such as reduced use of solvents, added to the increase of the powerfulness of analytical instrumental techniques should be encourage in order to improve the forensic entomotoxicology approach.

Evisceration residues from hunted roe deer as a resource for necrophagous insect fauna in the Black Forest, Germany: a preliminary study

Carrion of wild ungulates is an important resource for microbes, invertebrates and vertebrates, and affects local plant communities and soils. Most wild ungulates in central Europe, however, are intensely hunted and removed from the ecosystem, thus not available as carrion. This study explores the use of evisceration residues as a resource by necrophagous insects in a temperate mountainous forest in Germany. We experimentally compared the relative abundance of necrophagous insects between sites of caged roe deer carcasses and evisceration residues of roe deer using pitfall‐traps. While evisceration residues were used by necrophagous insects, significantly more individuals were sampled at entire deer carcasses; when corrected for biomass, however, no significant difference in abundance for Coleoptera groups was found. Overall, evisceration residues were used earlier and for a shorter period than entire deer carcasses. Leaving evisceration residues on site where game animals are obtained might help maintain specialized necrophagous insect communities, although their ecological role cannot completely replace that of whole carcasses of wild ruminants.

Experimental Evidence of Bone Lesions Due to Larder Beetle Dermestes maculatus (Coleoptera: Dermestidae).

Simple SummaryLarvae of the larder beetle Dermestes maculatus (Coleoptera: Dermestidae, De Geer, 1774) resemble caterpillars but actually feed on dry tissues of dead animals, and sometimes on human corpses. To hide and metamorphose into adult beetles, these larvae dig deep tunnels called pupation chambers. These holes and pits are usually observed in skins, horns, furs, or surrounding materials such as wood. They have also been reported on archaeological bones and experimentally observed on fresh pig bones, but never on humans. In this context, we investigated whether larder beetle larvae could also dig pupation chambers in human bones, and under which conditions this could occur. For this purpose, we placed medieval dry human bones as well as fresh calf and beef bones (control) with Dermestes maculatus larvae. After 1 month, we observed tunnels corresponding to pupation chambers only on dry human bones, and under conditions of high larval density. Despite these results being preliminary, they are, nonetheless, of particular interest in a forensic context, as they could help to understand taphonomic bone modifications or even the chronology of mass grave deposals.Dermestid beetles (Coleoptera: Dermestidae) are necrophagous insects feeding on mummified carcasses. After six to seven molts, the larvae stop feeding and dig pupation chambers to hide and safely evolve into adults. Such pupation chambers have already been observed on archaeological mammals’ bones, but the attribution and interpretation of these osteological lesions lack experimental evidence in a forensic context. To observe whether dermestid larvae dig pupation chambers in human bones, 20 or 40 Dermestes maculatus (De Geer, 1774) larvae were placed in a dermestarium with different types of bones varying in species (Bos taurus or human), age (adult or immature), and preservation method (fresh or dry). Our results show that dermestid larvae caused multiple lesions, including larval mandible traces on cortical bone, cortical perforations, drilling of pupation chambers, destruction of the trabecular network, and the perforation of cartilage. Bone destruction was mainly observed on aged dry bones, while fresh bones only exhibited soft tissue and superficial cartilage lesions. According to these results, pupation chambers could indicate the simultaneous presence of several corpses at different decomposition stages, or the addition of new corpses while others were already skeletonized. These conclusions are particularly important in the case of mass graves, where chronology is sometimes difficult to establish.

Carrion flies (Insecta: Diptera) found on human cadavers in Chiba prefecture, Honshu, Japan, with the first record of Fannia prisca from a human corpse.

Forensic entomology (FE) involves the collection and analysis of necrophagous insects and arthropods for postmortem interval estimation based on their growth and succession. In Japan, research on FE is limited, and the predominant species of necrophagous insects and their distribution have not been clarified. The present study aimed to clarify the actual situation of insects, targeting Diptera collected from human cadavers, in Chiba Prefecture. We targeted the cases for which specimens could be collected from forensic autopsies conducted at the Legal Medicine Department of Chiba University Graduate School of Medicine or from human bodies handled by the Chiba Police in 2019. We specifically chose cases from which adult insects could be bred. Fifty cases were applicable, and 47 cases were successful in rearing adult flies. Sixteen species of Diptera were identified: six species of Calliphoridae, four species of Sarcophagidae, and a few species of Fanniidae, Muscidae, Phoridae, Piophilidae, and Stratiomyidae. The most frequently observed species were Lucilia sericata (20 cases) and Chrysomya pinguis (18 cases). For the first time, globally, we recorded the presence of Fannia prisca in a human cadaver. In conclusion, this is the first report to reveal the presence of carrion flies in human death cases in Chiba Prefecture, Japan. Research in FE is important in the context of the Japanese natural and social environment since this can aid forensic investigations conducted by authorities.

Entomological identification of the post-mortem colonization of wolf cadavers in different decomposition stages

Human-driven biodiversity loss is progressively becoming a problem with dramatic consequences for the conservation of vital ecosystems. The increasing number of illegal killings of the grey wolf (Canis lupus, Linnaeus, 1758), a threatened species, displays the need for investigation and prosecution of such offences. Forensic entomology makes use of the knowledge about necrophagous insects to estimate a minimum time-since-death interval of the deceased person or animal, which can give important information on a possible perpetrator. The cadaver fauna along five decomposition stages of wolves in Germany was investigated in the period 2014–2021. The insects from 70 wolf cadavers, originating from all over Germany, were provided by the Leibniz Institute for Zoo and Wildlife Research Berlin. The accumulated degree day (ADD) model was applied for the post-mortem interval estimation on wolf cadavers for the first time. A total of 20 coleopteran species and 14 different dipteran species were discovered and identified. Almost 99 % of all insect specimens were from the order of Diptera, and beetles (Coleoptera) accounted for only 1 % of the cadaver fauna. The blowflies (Calliphoridae) are of particular importance for forensic issues, accounting for about 66 % of all families. Carrion beetles (Silphidae) were found as the second most abundant family (about 21 %). In addition, combining all cases, a steadily increasing insect species richness S was detected from early decay to advanced decay (fresh S = 8; bloated S = 12; active decay S = 21; advanced decay S = 34). In the following remains stage, the species number decreased again (S = 24). However, no significant difference in the number of species was found between the stages of decay when the cases were considered individually. The temporal pattern of insect appearance was found to be congruent with those of previous studies. Furthermore, a time of death was determined for each case and compared to the pathologist's estimates. This study provides insights into the arthropod fauna of wolf remains for the first time, applies the ADD-Model for post-mortem interval estimation, and discusses the suitability of forensic entomology for wildlife death investigations.

Vertebrate and invertebrate competition for carrion in human‐impacted environments depends on abiotic factors

AbstractHuman altered landscapes have caused declines in the diversity of wildlife where behaviorally plastic species (i.e., mesocarnivores and invasive species) tend to monopolize these areas and consume predictable and readily accessible food resources, such as human food waste and carrion. Increased consumption of carrion by vertebrates and invasive invertebrate species can alter population dynamics of native necrophagous insects relying on these resources. We tested the hypothesis that vertebrate scavengers and invasive species reduce blow fly (1) ability to use carrion and (2) reproduction in human‐impacted environments in central Texas, USA, with season, habitat (field and wooded landscapes), and carrion type (species of carrion and coat color) acting synergistically. Vertebrate scavengers in this habitat, of which 75% of the documented species were mesocarnivores and obligate scavengers, consumed 100% of carrion during the winter and 62% during summer despite having low species richness (2–5 species). Of the remaining carcasses available for arthropod activity during summer, the invasive red imported fire ant, Solenopsis invicta (Hymenoptera: Formicidae), monopolized 34%, and blow flies (e.g., Lucilia eximia and Chrysomya rufifacies [Diptera: Calliphoridae]) were only able to colonize 25%. Approximately 90% of carrion that was utilized by blow flies was co‐colonized by fire ants, and subsequent production of adult blow flies experienced up to a ninefold reduction in production compared with carcasses that were not scavenged by vertebrates or fire ants. Our results demonstrate oviposition resources used by blow flies in environments altered by human activity are reduced significantly by vertebrate scavengers and an invasive ant species. Future research should determine whether competitive interactions between vertebrate and invasive ant competitors for access to carrion resources have population‐level impacts to blow flies in human‐mediated ecosystems, or whether blow flies are able to shift to other resources to maintain sustainable populations and continue providing ecosystem services, such as pollination.

"Salt mummification" - atypical method of embalming a corpse.

It is extremely rare for table salt to be used to preserve a dead body in criminal cases. In the case presented here, after the death of his 85-year-old mother, a son kept her body preserved in table salt for about 2years to extort social benefits (pension). Before her death, the woman had been hospitalised twice due to chronic diseases. The case has been examined by the multi-disciplinary team. The unusual conditions in which the corpse was stored influenced its good condition (close to mummification), with limited colonisation of the corpse by necrophagous insects and insects involved in soft tissue biolysis (i.e. selected Diptera or Coleoptera). The use of table salt inhibited the growth of most fungi which would normally be present on a corpse stored in ambient conditions, and the corpse's surface was colonised by halophilic fungus (Scopulariopsis brevicaulis).

A Fly in the Ointment: How to Predict Environmentally Driven Phenology of an Organism That Partially Regulates Its Microclimate

Phenological models representing physiological and behavioral processes of organisms are used to study, predict, and optimize management of ecological subsystems. One application of phenological models is the prediction of temporal intervals associated with the measurable physiological development of arthropods, for the purpose of estimating future time points of interest such as the emergence of adults, or estimating past time points such as the arrival of ovipositing females to new resources. The second of these applications is of particular use in the conduct of forensic investigations, where the time of a suspicious death must be estimated on the basis of evidence, including arthropods with measurable size/age, found at the death scene. Because of the longstanding practice of using necrophagous insects to estimate time of death, standardized data and methods exist. We noticed a pattern in forensic entomological validation studies: bias in the values of a model parameter is associated with improved model fit to data, for a reason that is inconsistent with how the models used in this practice are interpreted. We hypothesized that biased estimates for a threshold parameter, representing the lowest temperature at which insect development is expected to occur, result in models’ accounting for behavioral and physiological thermoregulation but in a way that results in low predictive reliability and narrowed applicability of models involving these biased parameter estimates. We explored a more realistic way to incorporate thermoregulation into insect phenology models with forensic entomology as use context, and found that doing so results in improved and more robust predictive models of insect phenology.

Forensic entomology in research and practice: an overview of forensic experts' perceptions and scientific output in Brazil.

Given the growing demands for standardization of procedures for collection, preservation, and identification of insect specimens, this study aimed to identify how forensic entomology is used in Brazil and the perceptions of professionals involved in this process. We conducted: (1) bibliometric survey of the scientific production of forensic specialists from 2001 to 2020; (2) questionnaire applied to forensic professionals to verify their perceptions about the use of entomological evidence in practice. An increase in publications on Forensic Entomology was noticed in the last 5years, mainly in the South and Northeast regions. Of the 82 respondents to the questionnaire, 62.8% deal with cadavers at least once a week, but 89.0% of the professionals who examine cadavers weekly find less than 10.0% colonized by insect larvae. Using entomological evidence to estimate PMI was mentioned by only 36.6% of the professionals. Most respondents stated no procedures related to collecting, handling, or identifying necrophagous insects in their daily practice. Regarding the chain of custody, 64.6% said they were aware of the changes in the regulations involving the collection and maintenance of forensic evidence. We emphasize the importance of collaboration between scientists at universities and crime scene examiners. Although the use of entomological evidence in criminal investigations in Brazil is still scarce, a growing interest in this area can be detected among forensic experts.

Species Composition and Succession of Necrophagous Insects on Small Buried Baits in China.

The postburial interval (PBI) can be inferred by using necrophagous insects colonizing the buried corpse. In different seasons, the species composition and succession of necrophagous insects on swine carrion (0.5-0.75 kg) buried at the depths of 30 cm and 60 cm in a Populus alba var. pyramidalis (Bunge, 1854) (Salicales: Salicaceae) grove of Shenyang, China from 2017 to 2019 were investigated. A total of 21 species of necrophagous insects belonging to 5 orders, 17 families were collected. Among them, the species of Phoridae and Platystomatidae were dominant at burial depth of 30 cm and 60 cm in summer and autumn. The species composition and time of colonization of necrophagous insects on the buried baits varied with seasons. Platystoma mandschuricum (Enderlein, 1937) (Diptera: Platystomatidae) and Aleochara puberula (Klug, 1833) (Coleoptera: Staphylinidae), the first arriving insects in spring, occurred on the baits for the longest time, from early June to early December. This work could provide reference data for the PBI estimation in Shenyang and similar geographical areas.

The effects of hydrated lime and bleach on carrion decomposition and associated insect succession

ABSTRACT Necrophagous insect species are used in forensic entomology to assist with the estimation of the minimum post-mortem interval (PMImin). However, chemical substances applied to a corpse in a bid to conceal remains may affect the attractiveness of a corpse to insects and consequently the insect succession and decomposition. This study investigated the potential for two readily obtainable substances, hydrated lime and bleach to affect decomposition and associated insect succession in porcine remains outdoors and above ground during autumn, winter and spring in the Geelong region of Victoria, Australia. The substances were correlated with a significantly longer pre-appearance interval (PAI) (>12 hours) and delayed oviposition during colder months. Further, remains deposited during autumn and spring did not skeletonize when substances were present. These findings show the importance of considering the presence of bleach and hydrated lime on remains when estimating PMI.

Biodiversity of Calliphoridae Flies in South Rajasthan in Relation to Their Importance in Forensic Entomology

The analysis of the insect community present on a decomposing corpse can often provide valuable forensic insights, especially the estimation of the time of death, or postmortem interval (PMI). Life cycle of forensic insect act as clocks which starts within few minutes or hours after death. Udaipur has a semi-arid and vegetative climate. Forensically important flies directly affected from particular environmental condition. The present results highlight the particularities of local insect fauna corpses from Southern Rajasthan and their possible role in forensic entomology. The main objective of this study was to collect necrophagous insects colonizing the corpses as well as to gather information about their potential role in crime investigation and know the succession and decomposition pattern of forensically important fauna of Calliphoridae on carcass. The different life stages of Calliphoridae were observed during experiment and also compare with another forensically important families of Diptera like Sarcophagidae, Mucidae etc. Calliphoridae is most abundant fly that visit the carrion.

FORENSE ENTOMOLOGY:

In the forensic entomological context, the study of arthropods and insects, linked to expert mechanisms ains to raise references and evidence that can be used or finalized by an inquiry investigation, demonstrating how proficient the association of Science with the legal environment can be. In recent years, with the advancement of Science and the enhancement of investigative means through television series, professional entomologists and Forensic Entomology have begun to again academic and scientific visibility. The insects known as scavengers feed on decomposing organic matter, this is because when the animal tissues enter into a state of putrefaction, it attracts an enormous number of species that seek such substrate as a food source or to guarantee the survival of their offspring, therefore, necrophagous insects are part of the cadaverous fauna, when there is no impediment to the natural process. Predisposed to the continued interest in line with this area of knowledge, through a bibliographic review, the advances and functionalities of Forensic Entomology in the scientific, legal and expert practice spheres will be addressed in the context, in search of producing instruments of criminal investigation, enabling the identification of corpses even in advanced states of decomposition, as well as estimating the individual’s after death interval, thus contributing to assist and sustain the judicial work in respect of life. According to the data collected, it is was possible to discover the factors that influence the identification of the corpse, as well as the location where the fact happened and the relevance of using insects as a basis elucidate abd support a criminal investigation. Thus, the study of the biological cicle, biology, ecology and taxonomy of cadaverous fauna is indispensable for de validation of the expert report and compliance with justice by the judiciary.

Bioerosion and palaeoecological association of osteophagous insects in the Maastrichtian dinosaur Arenysaurus ardevoli

Bioerosions produced by the osteophagous diet of animals that fed on dinosaur bones are very scarce in the European fossil record. Herein we present bioerosion on hadrosaurid remains from the Maastrichtian Tremp Formation of the Pyrenean Basin, which is only the second such case recorded from the Iberian-Occitan Plate besides a sauropod from the Jurassic-Cretaceous of Valencia. The hadrosaurid fossil record is particularly rich in the Blasi sites of the Tremp Formation located in the municipality of Arén (Huesca, Spain). In this article, bones referred to the hadrosaurid Arenysaurus ardevoli from the Blasi-3 site are analysed to shed light on the palaeoenvironment and on the presence of a palaeoecological interaction between the hadrosaurid carcase and osteophagous tracemakers. Bioerosions recorded on the bones comprise tunnels, roundish holes, and straight notches, similar to the traces attributed to necrophagous insects (cf. Cuniculichnus seilacheri). Here, we record the first instance of the activity of these animals on dinosaur bones in the Upper Cretaceous of the Ibero-Occitan Plate. The results presented lead us to infer that the Arenysaurus bones were possibly transported by a storm or similar event to the Blasi-3 site, where they were exposed to post-mortem biotic interactions (eaten and partially decomposed by dermestid beetles) for a prolonged time period before they were completely buried.

The Effects of Chemicals Used For Suicide on Insect Succession, Diversity and Development: An Animal Model

It has proven that the presence of different chemicals can affect the succession patterns of necrophagousinsects. A comprehensive study was designed on the effects of nortriptyline, diazinon, and aluminumphosphate on arthropod’s succession and diversity on cadavers.Sixteen rabbits in two groups were used as a model in this study, 12 of them were treated with the drugsand were placed in two habitats (sun and shade) based on the study design. For each group, one cagewas considered as control. Insects were collected twice a day from the cadavers and identified.In total, 549 necrophagous insects from five families, were collected from all the carcasses. Chrysomyaalbiceps was the dominant insect on all cadavers, expect for one treated with diazinon, in which it wasdisplaced by Dermestes frischii. The highest number of insects were collected on the sixth day for allcadavers. The majority were collected from the shaded cages.Generally, the species diversity was higher for all the cadavers treated with the drugs compared to thecontrol cadavers. The results showed that the presence of diazinon in the cadaver can repel necrophagousinsects, on the contrary nortriptyline seems to attract more species/specimen.