Diatoms in maggots; a potential tool for drowning diagnosis - A preliminary study

Advanced putrefaction causes extensive loss of soft tissue, rendering it difficult to use the diatom test as a reliable diagnostic tool for drowning investigations. A positive diatom test in carrion insect larvae may provide significant assistance in overcoming the challenge of decomposition. The studies determined the utility of diatom test in carrion larvae on severely decomposed bodies. A modified acid digestion method involving nitric acid, K2Cr2O7 and HCl, was used to digest the blowfly larvae feeding on piglet carrion previously drowned in freshwater and sea water, respectively. Extracted diatom frustules were analysed and characterised using light microscopy coupled to a digital camera. Diatoms recovered from maggots on sea-drowned piglets were similar to diatoms from sea water (drowning medium). Centric diatoms recovered in maggots were higher (200 ± 60 diatoms/ mL) than pennate diatoms (80 ± 20 diatoms/mL). Isolated diatoms common to both maggots and water samples included Coscinodiscus sp. and Navicular spp. Albeit, there were no diatoms recovered from maggots on freshwater-drowned piglets. The findings of this study suggest that the diatom test is still a reliable diagnostic tool to determine if drowning was involved in the death of a fully decomposed body. This is the first study that isolated diatoms from maggots feeding on drowned bodies. It serves as the basis for further research into the utility of maggots for drowning investigations.

A preliminary study of carrion insects in Greece and their attraction to three animal baits: a forensic entomology perspective

The current study provides data on the composition of the dipteran and coleopteran fauna attracted to three different animal baits (chicken stomach, beef liver, fish) in the urban ecosystem of Athens, Greece. An additional objective was to examine the effect of bait choice by the collected taxa. Three trap locations were established within the Agricultural University of Athens. At each location two different types of baited traps were used to capture and record the local dipteran and coleopteran biodiversity. During the sampling period, a total of 2416 dipteran and coleopteran specimens representing 43 species were collected and identified. The three most abundant dipteran taxa were Sarcophaga sp. (Diptera: Sarcophagidae), Calliphora vicina Robineau-Desvoidy, Lucilia sericata (Meigen) (Diptera: Calliphoridae). The results showed that the structure of the local insect community associated with the decomposition of animal baits depends on the bait used for sampling. This study reinforced the feasibility of using animal tissues as attractants to a wide diversity of medical, parasitological and forensically important taxa. Overall, beef liver attracted the most insects with Diptera preferring beef liver and Coleoptera preferring chicken stomach. Furthermore, this study revealed that baits of one animal tissue did not attract all species but in combination a much better understanding of this biodiversity was achieved. Finally, from a forensic entomology perspective this study highlights the lack of understanding of the value of entomological data related to case work in Greece.

Eye and hair color prediction of human DNA recovered from Lucilia sericata larvae

Forensic entomological evidence is employed to estimate minimum postmortem interval (PMImin), location, and identification of fly samples or human remains. Traditional forensic DNA analysis (i.e., STR, mitochondrial DNA) has been used for human identification from the larval gut contents. Forensic DNA phenotyping (FDP), predicting human appearance from DNA-based crime scene evidence, has become an established approach in forensic genetics in the past years. In this study, we aimed to recover human DNA from Lucilia sericata (Meigen 1826) (Diptera: Calliphoridae) gut contents and predict the eye and hair color of individuals using the HIrisPlex system. Lucilia sericata larvae and reference blood samples were collected from 30 human volunteers who were under maggot debridement therapy. The human DNA was extracted from the crop contents and quantified. HIrisPlex multiplex analysis was performed using the SNaPshot minisequencing procedure. The HIrisPlex online tool was used to assess the prediction of the eye and hair color of the larval and reference samples. We successfully genotyped 25 out of 30 larval samples, and the most SNP genotypes (87.13%) matched those of reference samples, though some alleles were dropped out, producing partial profiles. The prediction of the eye colors was accurate in 17 out of 25 larval samples, and only one sample was misclassified. Fourteen out of 25 larval samples were correctly predicted for hair color, and eight were misclassified. This study shows that SNP analysis of L. sericata gut contents can be used to predict eye and hair color of a corpse.

A beetle for prosecution: exogenous DNA detection from larval and adult gut of a Neotropical carrion beetle

The use of recovered DNA ingested by necrophagous or hematophagous insects has increased in forensic sciences, mainly with representatives of flies. However, some beetles are also important for medico-legal forensic entomology because they feed on carcasses until advanced decomposition. This study evaluated whether the Neotropical carrion beetle Oxelytrum discicolle (Silphidae) has the potential for the detection of exogenous DNA into the gut. The whole gut or the gut contents were extracted from O. discicolle larvae and adult previously fed on pig carcass. The pig DNA recovery rate was 33.3% in larvae and 25% in adults, indicating that the carrion beetle's gut may be useful for DNA identification of ingested food. Samples with the whole gut or only gut contents showed the same DNA recovery rate. Exogenous DNA from the whole gut was recovered from samples stored in ethanol at -20 ºC for 11 days, showing that samples of O. discicolle can be stored in the forensic laboratory without loss in DNA recovery rate.

Comparison of DNA extraction techniques for the recovery of bovine DNA from fly larvae crops

Forensic entomology aids investigations using insects and is primarily associated with the estimation of post-mortem interval (PMI). Studies have shown that human DNA can be recovered from the crops of fly larvae. While several factors regarding the recovery of human DNA from crops have been studied, DNA extraction methods have not been thoroughly assessed. Determining a method for optimal extraction could aid crime laboratories in implementing DNA extraction from larvae and streamlining future research. Bovine DNA was used as a substitute for human DNA to test several DNA extractions kits. Four DNA extraction kits (Chelex®, PDQeX forensicGEM, EZ1® DNA Investigator, DNeasy® Powersoil® Pro Kit) were evaluated based on the quantity and quality of bovine DNA extracted. Extractions were performed on whole fly larvae and dissected crops. Quantification was performed using real-time PCR (qPCR) on a StepOne™ Real-Time PCR System with SYBR® Green using bovine-specific cytochrome b primers. The quality of extracts was determined by checking for inhibition using commercial qPCR chemistries with an internal PCR control (IPC). When using whole fly larvae, Powersoil® Pro yielded the highest average DNA yield (n = 10, 0.668 ± 0.458 ng/μl), while EZ1® DNA Investigator yielded the highest average with crops (n = 10, 0.605 ± 0.403 ng/μl). Chelex and forensicGEM yielded low amounts of bovine DNA, and its extracts were inhibited, unlike EZ1® and Powersoil® Pro, which have purification steps. Therefore, it is recommended to use EZ1® DNA Investigator coupled with automation on EZ1® Advanced XL to recover DNA from fly larvae crops.

Molecular identification of the potentially forensically relevant cluster flies Pollenia rudis (Fabricius) and Pollenia vagabunda (Meigen) (Diptera: Polleniidae) — non-recorded species in Algeria

Cluster flies are represented by the genus Pollenia Robineau-Desvoidy, 1830 of the family Polleniidae Brauer and Bergenstamm, 1889. Their larvae are known to be internal parasites or predators of earthworms. Herein, we report for the first time the occurrence of the cluster flies Pollenia rudis Fabricius, 1794 and Pollenia vagabunda (Meigen, 1826) (Diptera: Polleniidae) on carcasses in Algeria and identify them through DNA barcoding. A region of the mitochondrial cytochrome c oxidase I gene (COI) was amplified and sequenced. Genetic distances were determined. A phylogenetic tree was constructed with the maximum parsimony method using 10 000 bootstrap replicates. A total number of 157 adults of P. rudis were collected together with 325 adults of Pollenia vagabunda. The occurrence of Pollenia on animal carcasses does not seem to be correlated with a particular stage of decomposition. All the sequences were correctly identified using the BLASTn tool from the GenBank database and the BOLD identification engine. Intra- and interspecific sequence divergence values were less than 1% and greater than 3%, respectively. COI barcodes obtained from this study were robust enough to identify and distinguish unambiguously between P. rudis and P. vagabunda. In the tree-based analysis, the cluster flies were all assigned to their respective species separately from each other confirming the morphological identification. These results provide DNA barcodes that contribute to the growth of reference databases and allow fast and accurate identification.

Role of Chrysomya albiceps (Diptera: Calliphoridae) and Musca domestica (Diptera: Muscidae) Maggot Crop Contents in Identifying Unknown Cadavers

Forensic entomology focuses on the analysis of insect larvae present at crime scenes to help identify unknown cadavers. Carrion-feeding maggots store food in a crop located at the anterior end of the gut. DNA recovered from the crop can be amplified, sequenced, and identified to determine the origin of the food. This information could help investigators to identify a missing victim if maggots are discovered at a crime scene in the absence of a corpse. Chrysomya albiceps (Wiedemann) and Musca domestica (Linnaeus) are primary forensic species. Little or no information on the identification of unknown cadavers using C. albiceps and M. domestica larvae is available, and we aimed to compare the effectiveness of using the crop contents of instars of C. albiceps and M. domestica larvae to identify corpses at different time intervals. Two hundred and forty larvae of both species were reared on rat and/or mouse liver, and DNA from crop contents was extracted after different time intervals from different instar larvae. DNA was amplified using specific primers that match the mitochondrial cytochrome oxidase subunit I (mt COI) gene of the food source. Results showed that food provided to larvae affected life span and the ability to be used to identify unknown cadavers. Chrysomya albiceps larvae proved more useful than M. domestica larvae. Moreover, crop contents of third instar larvae of both species fed for 24 h are more useful than contents from other time intervals in identifying unknown tissues. Results are promising and may help investigators to identify unknown/missing victims.

Analysis of the 13C isotope ratios of amino acids in the larvae, pupae and adult stages of Calliphora vicina blow flies and their carrion food sources

Adult blow flies are one of the first necrophagous insects to colonize fresh carcasses. The eggs they lay hatch into larvae, which then feed on the decomposing body. Like all organisms, blow flies "are what they eat," meaning that the isotopic composition of their body tissues reflects their diet. This manuscript combines ecology with a forensic application by using isotope ratio mass spectrometry (IRMS) to understand the relationship between the δ¹³C of amino acids in different carrion sources and the blow fly that feed on them. We also measure the amino acid-level fractionation that occurs at each major life stage of the blow flies. Adult blow flies from a commercial strain of Calliphora vicina (Robineau-Desvoidy) (Diptera: Calliphoridae) oviposited on raw pork muscle, beef muscle, or chicken liver. Larvae, pupae, and adult blow flies from each carrion were selected for amino acid compound-specific isotope analysis. Canonical discriminant analysis showed that flies were correctly classified to specific carrion types in 100% (original rules) and 96.8% (leave-one-out cross-validation [LOOCV]) of cases. Regarding life stages, we obtained 100% and 71% of correct classification in original rules and LOOCV, respectively. The isotope ratios of most of the essential amino acids did not significantly change between life stages (at 95% CI). However, some non-essential amino acids (Ala, Ser, and Glu) and some conditionally essential amino acids (Gly and Pro) were isotopically depleted in the adult stage. Except for the essential amino acids, the amino acids in larvae and pupae were enriched in ¹³C, and adult blow flies were depleted in ¹³C relative to the carrion on which they fed. These results make it possible to exclude potential sources of carrion as larval food. Amino acid-specific IRMS could help inform entomologists whether a fly has just arrived from another location to feed on a corpse or has emerged from a pupa whose feedstock was the corpse. Such insight could enhance the significance of blow flies for post-mortem interval determinations. The analytical ability to link organisms from one trophic level to another through the use of compound-specific isotope analysis of amino acids could have wide-reaching consequences in a variety of disciplines. Graphical abstract ᅟ.

Isolation, identification, and time course of human DNA typing from bed bugs, Cimex lectularius

Bed bugs (Cimex lectularius L.) are ectoparasitic wingless insects that feed on the blood of mammals, typically in residential settings. The objectives of this study were to establish a time-course of human DNA quantitation from bed bugs and to generate human DNA profile(s) of a host and/or multiple hosts from a bed bug that fed on human blood. Female human genomic DNA concentrations ranged from 18.370 to 0.195ng/bed bug at 0-108h post blood meal (PBM), male human genomic DNA concentrations ranged from 5.4 to 0.105ng/bed bug at 0-108h PBM, and pooled human female and male blood ranged from 5.49 to 0.135ng/bed bug at 0-96h PBM. Human autosomal STR complete profiles were obtained until 72h PBM for female, male, and pooled human blood. These results reveal that identification of multiple human hosts is possible from a single bed bug. However, the ratio of each contributor may be variable depending on the amount of blood ingested from each individual and the time difference of blood consumed from each subject. Average peak heights for three STR markers of low (D3S1358), medium (D13S317), and high molecular weight (D2S1338), were also compared over time. Peak heights were consistently higher for the low molecular weight marker over all time intervals. These data suggest that some markers can be successfully recovered more than three days PBM. Hence, bed bugs can serve as physical evidence in temporal and spatial predictions to match suspects and/or victims to specific locations in criminal investigations.

Which mosquitoes (Diptera: Culicidae) are candidates for DNA extraction in forensic practice?

Mosquitoes can be of importance in forensic context as a source of the perpretator's DNA. The aim of this study was to find how can we optimize the selection of appropriate mosquito individuals. The study was based on the data of 177833 trapped female mosquitoes and 105236 individuals which were collected directly from human skin. The mean human-specific biting willingness value of Aedes species was the highest (mean: 0.8). Significant differences were found between the human-specific biting willingness value variances of Aedes and Culex (p=0.0117) and barely significant differences between Anopheles and Culiseta (p = 0.5412), as well as between Aedes and Culiseta genera (p = 0.0562). Culiseta species showed the lowest human-specific biting willingness values (mean = 0.16). The mean of the human-specific biting willingness values of univoltine and multivoltine mosquitoes were 0.43 and 0.37 which means no significant difference between the variances of the two groups (p = 0.625). The mean of the human-specific biting willingness values of the predominantly mammal biting and non-mammal biting mosquitoes were 0.45 and 0.03 with a very significant difference (p<0.0001). Only five mosquito species have a relative biting risk index equal or more than 0.03 in Hungary, namely of Aedes vexans (0.43), Ochlerotatus cantans: (0.25), Ochlerotatus sticticus: (0.11), Culex modestus: (0.07) and Aedes cinereus: (0.03). It can be concluded that the mean human-specific biting willingness of mosquitoes depends on the genera, the host preference and it is independent of the annual number of generations or the breeding habitat preference. The relative biting risk index reflects the actual and annual relative abundances and the usefulness and availability of a mosquito for legal purposes reducing the financial and time requirements of the investigations.

A brief review of forensically important flesh flies (Diptera: Sarcophagidae)

Forensic entomology could provide valuable data for the minimum postmortem interval (PMImin) estimation and other relevant information, such as causes and circumstances of death. Some representatives of flesh flies are one of the dominant necrophagous insects during early stages of decomposition, demonstrating unique biological characteristics compared with other necrophagous flies. Moreover, they lead to global health concerns as carriers of various pathogenic micro-organisms, and dominantly result in the traumatic myiasis. Thus, sarcophagid flies are considered important in decomposition processes for PMImin estimation. However, the utility of sarcophagid flies has been seriously hampered by limited ecological, biological and taxonomic knowledge of them. The aim of this paper is to provide a brief review on the species, distribution and biological habit of forensically important sarcophagid flies. In addition, the relation between traumatic myiasis and flesh flies, molecular identification methods and developmental pattern of flesh flies are summarized.

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

The use of insects as indicators of post-mortem displacement is discussed in many texts, courses and TV shows, and several studies addressing this issue have been published. Although the concept is widely cited, it is poorly understood, and only a few forensic cases have successfully applied such a method. The use of necrophagous insects as evidence of cadaver relocation actually involves a wide range of biological aspects. Distribution, microhabitat, phenology, behavioral ecology, and molecular analysis are among the research areas associated with this topic. This article provides the first review of the current knowledge and addresses the potential and limitations of different methods to evaluate their applicability. This work reveals numerous weaknesses and erroneous beliefs as well as many possibilities and research opportunities.

Forensic Entomology in Animal Cruelty Cases

Forensic entomology can be useful to the veterinary professional in cases of animal cruelty. A main application of forensic entomology is to determine the minimum postmortem interval by estimating the time of insect colonization, based on knowledge of the rate of development of pioneer colonizers and on insect species succession during decomposition of animal remains. Since insect development is temperature dependent, these estimates require documentation of the environmental conditions, including ambient temperature. It can also aid in the detection and recognition of wounds, as well as estimate the timing of periods of neglect. Knowledge of the geographic distribution of insects that colonize animal remains may suggest that there has been movement or concealment of the carcass or can create associations between a suspect, a victim, and a crime scene. In some instances, it can aid in the detection of drugs or toxins within decomposed or skeletonized remains. During animal cruelty investigations, it may become the responsibility of the veterinary professional to document and collect entomological evidence from live animals or during the necropsy. The applications of forensic entomology are discussed. A protocol is described for documenting and collecting entomological evidence at the scene and during the necropsy, with additional emphasis on recording geographic location, meteorological data, and collection and preservation of insect specimens.

Human identification by lice: A Next Generation Sequencing challenge

Rapid and progressive advances in molecular biology techniques and the advent of Next Generation Sequencing (NGS) have opened new possibilities for analyses also in the identification of entomological matrixes. Insects and other arthropods are widespread in nature and those found at a crime scene can provide a useful contribution to forensic investigations. Entomological evidence is used by experts to define the postmortem interval (PMI), which is essentially based on morphological recognition of the insect and an estimation of its insect life cycle stage. However, molecular genotyping methods can also provide an important support for forensic entomological investigations when the identification of species or human genetic material is required. This case study concerns a collection of insects found in the house of a woman who died from unknown causes. Initially the insects were identified morphologically as belonging to the Pediculidae family, and then, human DNA was extracted and analyzed from their gastrointestinal tract. The application of the latest generation forensic DNA assays, such as the Quantifiler(®) Trio DNA Quantification Kit and the HID-Ion AmpliSeq™ Identity Panel (Applied Biosystems(®)), individuated the presence of human DNA in the samples and determined the genetic profile.

Four Forensic Entomology Case Studies: Records and Behavioral Observations on Seldom Reported Cadaver Fauna With Notes on Relevant Previous Occurrences and Ecology

A yearlong survey of insect taxa associated with human decomposition was conducted at the Southeast Texas Applied Forensic Science (STAFS) facility located in the Center for Biological Field Studies of Sam Houston State University in Huntsville, TX. During this study, four insect-cadaver interactions were observed that represent previously poorly documented yet forensically significant interactions: Syrphidae maggots colonized a corpse in an aquatic situation; Psychodidae adults mated and oviposited on an algal film that was present on a corpse that had been recently removed from water; several Panorpidae were the first insects to feed upon a freshly placed corpse in the autumn; and a noctuid caterpillar was found chewing and ingesting dried human skin. Baseline knowledge of insect-cadaver interactions is the foundation of forensic entomology, and unique observations have the potential to expand our understanding of decomposition ecology.

The molecular systematics of blowflies and screwworm flies (Diptera: Calliphoridae) using 28S rRNA, COX1 and EF-1α: insights into the evolution of dipteran parasitism

The Calliphoridae include some of the most economically significant myiasis-causing flies in the world - blowflies and screwworm flies - with many being notorious for their parasitism of livestock. However, despite more than 50 years of research, key taxonomic relationships within the family remain unresolved. This study utilizes nucleotide sequence data from the protein-coding genes COX1 (mitochondrial) and EF1α (nuclear), and the 28S rRNA (nuclear) gene, from 57 blowfly taxa to improve resolution of key evolutionary relationships within the family Calliphoridae. Bayesian phylogenetic inference was carried out for each single-gene data set, demonstrating significant topological difference between the three gene trees. Nevertheless, all gene trees supported a Calliphorinae-Luciliinae subfamily sister-lineage, with respect to Chrysomyinae. In addition, this study also elucidates the taxonomic and evolutionary status of several less well-studied groups, including the genus Bengalia (either within Calliphoridae or as a separate sister-family), genus Onesia (as a sister-genera to, or sub-genera within, Calliphora), genus Dyscritomyia and Lucilia bufonivora, a specialised parasite of frogs and toads. The occurrence of cross-species hybridisation within Calliphoridae is also further explored, focusing on the two economically significant species Lucilia cuprina and Lucilia sericata. In summary, this study represents the most comprehensive molecular phylogenetic analysis of family Calliphoridae undertaken to date.

Recovery of environmental human DNA by insects

We tested the hypotheses that foraging insects can acquire human DNA from the environment and that insect-delivered human DNA is of sufficient quantity and quality to permit standard forensic analyses. Houseflies, German cockroaches, and camel crickets were exposed to dusty surfaces and then assayed for human mitochondrial and nuclear loci by conventional and qPCR, and multiplex STR amplification. Over two experiments, 100% of insect groups and 94% of dust controls tested positive for human DNA. Of 177 individuals, 33-67% tested positive and 13 yielded quantifiable human DNA (mean = 0.022 ± 0.006 ng; mean dust control = 2.448 ± 0.960 ng); four had at least one positive allele call for one or more locus; eight others showed multiple peaks at some loci. Results imply that application to routine forensic casework is limited given current detection methodology yet demonstrate the potential use of insects as environmental samplers for human DNA.

Survey of the genetic diversity of Phormia regina (Diptera: Calliphoridae) using amplified fragment length polymorphisms

There is very little information concerning carrion fly population genetic structure. We generated amplified fragment length polymorphism (AFLP) profiles for the common blowfly, Phormia regina (Meigen), from sites spanning the contiguous United States. Analysis of molecular variance (AMOVA) based on 232 loci found significant variation (phi(SC) = 23%) among discrete samples (those collected at a bait in one location over a short period of time). Samples collected in the same location but at different times were also distinct. When samples were pooled into geographic regions (east, central, west), the variation was negligible (phi(CT) = 0%). A Mantel test found only a very weak correlation between individual genetic and geographic distances. Relative relatedness coefficients based on shared allele proportions indicated individual samples were likely to contain close relatives. P. regina arriving at an individual carcass typically represent a nonrandom sample of the population despite a lack of geographic structure. A female blow fly produces hundreds of offspring at one time; therefore, newly emerged siblings may respond in concert to an odor plume. These results may be of interest to forensic entomologists, many of whom use a laboratory colony founded from a small sample for the growth studies that support casework. Discrepancies between published growth curves may reflect such random differences in the founding individuals.

Application of DNA-based methods in forensic entomology

A forensic entomological investigation can benefit from a variety of widely practiced molecular genotyping methods. The most commonly used is DNA-based specimen identification. Other applications include the identification of insect gut contents and the characterization of the population genetic structure of a forensically important insect species. The proper application of these procedures demands that the analyst be technically expert. However, one must also be aware of the extensive list of standards and expectations that many legal systems have developed for forensic DNA analysis. We summarize the DNA techniques that are currently used in, or have been proposed for, forensic entomology and review established genetic analyses from other scientific fields that address questions similar to those in forensic entomology. We describe how accepted standards for forensic DNA practice and method validation are likely to apply to insect evidence used in a death or other forensic entomological investigation.

The evolution of myiasis in blowflies (Calliphoridae)

Blowflies (Calliphoridae) are characterised by the ability of their larvae to develop in animal flesh. Where the host is a living vertebrate, such parasitism by dipterous larvae is known as myiasis. However, the evolutionary origins of the myiasis habit in the Calliphoridae, a family which includes the blowflies and screwworm flies, remain unclear. Species associated with an ectoparasitic lifestyle can be divided generally into three groups based on their larval feeding habits: saprophagy, facultative ectoparasitism, and obligate parasitism, and it has been proposed that this functional division may reflect the progressive evolution of parasitism in the Calliphoridae. In order to evaluate this hypothesis, phylogenetic analysis of 32 blowfly species displaying a range of forms of ectoparasitism from key subfamilies, i.e. Calliphorinae, Luciliinae, Chrysomyinae, Auchmeromyiinae and Polleniinae, was undertaken using likelihood and parsimony methods. Phylogenies were constructed from the nuclear 28S large subunit ribosomal RNA gene (28S rRNA), sequenced from each of the 32 calliphorid species, together with suitable outgroup taxa, and mitochondrial cytochrome oxidase subunit I and II (COI+II) sequences, derived primarily from published data. Phylogenies derived from each of the two markers (28S rRNA, COI+II) were largely (though not completely) congruent, as determined by incongruence-length difference and Kishino-Hasegawa tests. However, the phylogenetic relationships of blowfly subfamilies based on molecular data did not concur with the pattern of relationships defined by previous morphological analysis; significantly, molecular analysis supported the monophyly of blowflies (Calliphoridae), distinct from the bot and warble flies (Oestridae). Comparative analysis of the myiasis habit based primarily on the 28S rRNA phylogeny indicated that obligate parasitism, and the ability to initiate myiasis in higher vertebrates, has multiple independent origins across myiasis-causing flies (Calliphoridae and Oestridae) and in at least three subfamilies of blowfly (Calliphoridae). Finally, the general association of various blowfly genera and subfamily clades with particular continental and geographical regions suggests that these groups probably came into existence in the Late Cretaceous period, following the break-up of Gondwana.

Molecular approaches to the study of myiasis-causing larvae

Among arthropod diseases affecting animals, larval infections - myiases - of domestic and wild animals have been considered important since ancient times. Besides the significant economic losses to livestock worldwide, myiasis-causing larvae have attracted the attention of scientists because some parasitise humans and are of interest in forensic entomology. In the past two decades, the biology, epidemiology, immunology, immunodiagnosis and control methods of myiasis-causing larvae have been focused on and more recently the number of molecular studies have also begun to increase. The 'new technologies' (i.e. molecular biology) are being used to study taxonomy, phylogenesis, molecular identification, diagnosis (recombinant antigens) and vaccination strategies. In particular, more in depth molecular studies have now been performed on Sarcophagidae, Calliphoridae and flies of the Oestridae sister group. This review discusses the most topical issues and recent studies on myiasis-causing larvae using molecular approaches. In the first part, PCR-based techniques and the genes that have already been analysed, or are potentially useful for the molecular phylogenesis and identification of myiasis-causing larvae, are described. The second section deals with the more recent advances concerning taxonomy, phylogenetics, population studies, molecular identification, diagnosis and vaccination.

The forensic entomologist in the context of the forensic pathologist's role

An adequate death investigation requires the combined efforts and cooperation of experts in different disciplines: crime scene technicians, death investigators, forensic pathologists, anthropologists, entomologists, other medical and non-medical professionals. These front-line experts play a crucial role in every death investigation process. The forensic pathologist normally has the legal authority to take charge of the dead body at a death scene and his primary functions are the exterior and interior examination of the cadaver by analyzing the extent of antemortem injuries and the postmortem changes and the recovery of physical evidence. He is responsible for determining how, when and why of any death which is the result of violence, suspicious or unexplained circumstances or a death which is sudden or unattended, defending and explaining the reasons for making these diagnoses in a courtroom. The forensic entomologist can provide invaluable aid in death cases where human remains are colonized by insects and in the overall investigation. His principal role is to identify the arthropods associated with such cases and to analyze entomological data for interpreting insect evidence. He is responsible for determining the period of insect activity according to all the variables affecting insect invasion of remains and their development. The major goal of medico-criminal entomology is to contribute to the determination of the time, cause, manner and place of the investigated death (especially on badly decomposed corpses or skeletonized human remains) with the support of all the elements which can be inferred from the study of insects found on the cadaver or nearby. The application of techniques devised recently in forensic entomology can allow experts in the field to collect strong entomological evidence and provide useful information not only in a death investigation including movement or storage of the remains following death, time of dismemberment, postmortem artifacts on the body but also at the scene, and even more in child neglect, sexual molestation and identification of suspects. As the role of the forensic entomologist at the death scene, at the autopsy and in the laboratory is defined and well known, this paper focuses on the difficulties that could arise if forensic pathologists and entomologists are uncertain about the procedures that they have to follow, do not realize the value of objective findings or fail to evaluate them. Although every forensic case presents a slightly different set of circumstances and has to be tackled individually, the forensic pathologist should work with the forensic entomologist from the visual observations of the cadaver on the scene, through the collection of arthropods and temperature data at the death scene and at the autopsy, up to the final report with the interpretation of entomological and other biological evidence.