Entomotoxicology

A review of multi-disciplinary decomposition research and key drivers of variation in decay

The decomposition of animal remains is a multifaceted process, involving ecological, biological, and chemical interactions. While the complexity is acknowledged through concepts like the necrobiome, it's unclear if this complexity is reflected in research. Appreciation of the complexity of decomposition is crucial for identifying sources of variation in estimations of time since death in medico-legal science, as well as building broader ecological knowledge of the decomposition process. To gain insights into the extent of multidisciplinary research in the field of decomposition science, we conducted an examination of peer-reviewed literature on four key drivers of variation: volatile organic compounds, microbes, drugs/toxins, and insects. Among 650 articles, we identified their scientific discipline, driver/s of variation investigated, and year of publication. We found that 19% explored relationships between two drivers, while only 4% investigated interactions between three. None considered all four drivers. Over the past three decades, there has been a steady increase in decomposition research publications, signifying its growing importance. Most research (79%) was linked to forensic science, highlighting opportunities for interdisciplinary collaboration in decomposition science. Overall, our review underscores the need to incorporate multidisciplinary approaches and theory into contemporary decomposition research.

Deciphering the impact of microenvironmental factors on cuticular hydrocarbon degradation in Lucilia sericata empty Puparia: Bridging ecological and forensic entomological perspectives using machine learning models

Blow flies (Calliphoridae) play essential ecological roles in nutrient recycling by consuming decaying organic matter. They serve as valuable bioindicators in ecosystem management and forensic entomology, with their unique feeding behavior leading to the accumulation of environmental pollutants in their cuticular hydrocarbons (CHCs), making them potential indicators of exposure history. This study focuses on CHC degradation dynamics in empty puparia of Lucilia sericata under different environmental conditions for up to 90 days. The three distinct conditions were considered: outdoor-buried, outdoor-above-ground, and indoor environments. Five predominant CHCs, n-Pentacosane (n-C25), n-Hexacosane (n-C26), n-Heptacosane (n-C27), n-Octacosane (n-C28), and n-Nonacosane (n-C29), were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). The findings revealed variations in CHC concentrations over time, influenced by environmental factors, with significant differences at different time points. Correlation heatmap analysis indicated negative correlations between weathering time and certain CHCs, suggesting decreasing concentrations over time. Machine learning techniques Support Vector Machine (SVM), Multilayer Perceptron (MLP), and eXtreme Gradient Boosting (XGBoost) models explored the potential of CHCs as age indicators. SVM achieved an R-squared value of 0.991, demonstrating high accuracy in age estimation based on CHC concentrations. MLP also exhibited satisfactory performance in outdoor conditions, while SVM and MLP yielded unsatisfactory results indoors due to the lack of significant CHC variations. After comprehensive model selection and performance evaluations, it was found that the XGBoost model excelled in capturing the patterns in all three datasets. This study bridges the gap between baseline and ecological/forensic use of empty puparia, offering valuable insights into the potential of CHCs in environmental monitoring and investigations. Understanding CHCs' stability and degradation enhances blow flies' utility as bioindicators for pollutants and exposure history, benefiting environmental monitoring and forensic entomology.

Effects of aluminium phosphide on larval morphometry of two important Chrysomya species

Chrysomya megacephala and C. rufifacies are globally predominant species of blowflies that are amongst the primary colonisers of decomposing carcasses. The development of blowflies has been studied extensively to estimate the minimum postmortem interval (PMImin). This article evaluates the effect of aluminium phosphide (AlP) on the larval morphometry and life cycles of C. megacephala and C. rufifacies. The rabbits were given different dosages of AlP and their livers were excised to rear C. megacephala and C. rufifacies. Through multiple-regression analysis, we assessed the overall impact of varying dosages of AlP on larvae of both species. AlP accelerated development until pupation, whilst the time until emergence remained the same. At higher concentrations, AlP had a positive effect on the development of these species. Since both species are abundant, forensic entomology studies examining the effect of AlP on morphometry and developmental stages would provide valuable information to investigators assessing PMImin.

Effects of Terbufos (Organophosphate) on Larval Behaviour of Two Forensically Important Diptera Species: Contributions for Entomotoxicology

Neurotoxicant compounds interfere with the behaviour and biology of insects, significantly altering their locomotion patterns. However, little is known about the effect of organophosphates, neurotoxicants for agricultural, domestic and industrial use, on the larval movement of necrophagous flies, although being responsible for frequent cases of poisoning and accidental or intentional deaths. Thus, we aimed to study the influence of Terbufos (organophosphate) on the activity and mobility patterns of Lucilia eximia (Wiedemann 1819) (Calliphoridae) and Peckia (Peckia) chrysostoma (Wiedemann 1830) (Sarcophagidae) immatures collected from rat carcasses intoxicated with 5, 10 or 20 mg/kg of Terbufos, to evaluate (i) peristaltic movements and body contractions, and (ii) distance and shape of the trajectory travelled by the larva. Behavioural parameters were analysed in loco and through videos. We observed that the presence of Terbufos altered poisoned larvae's activity and body mobility in both taxon and dose-dependent manner. Lucilia eximia larvae were more active, with greater frequency of body movements and lateral contractions when intoxicated with high and intermediate doses of Terbufos. On the other hand, P. (P.) chrysostoma immatures were less active, with fewer body and lateral contractions when intoxicated with the high dose of the compound. This work experimentally demonstrates that the presence of Terbufos can alters the mobility and movement of intoxicated necrophagous Diptera, essential components of the cadaveric fauna.

Validation of a new method for the detection of Ethyl glucuronide in larvae of Lucilia sericata as a marker of ante-mortem alcohol consumption

Larvae and insects are an important and alternative biological matrix in the development anpost-mortem forensic toxicology. They are very useful when conventional matrices are not available, in particular when the loss of biological fluids, due to the decomposition of corpses or to a traumatic death, occurs. The purpose of this study is to develop and validate an analytical method in Ultra High-Performance Liquid Chromatography at High Resolution Mass Spectrometry (HPLC/HR-MS) for the research and quantification of Ethyl glucuronide (EtG) on larvae. The criteria taken into consideration for the validation are linearity, quantitation limits (LOD and LLOQ), accuracy, precision, carryover, interferences and ionization suppression/enhancement. The method was shown to be linear within the tested range, with a coefficient of determination higher than 0.99. LOD was 2 pg mg-1, while LLOQ was 5 pg mg-1. Accuracy, precision and ionization/suppression enhancement fulfilled the criteria indicated in the guidelines used for the validation. The establishment and validation of this method allowed the identification of Ethyl glucuronide on the larvae of Lucilia sericata (Calliphoridae) of a subject found death in an advanced state of decomposition.

Assessment of Fungal Succession in Decomposing Swine Carcasses (Sus scrofa L.) Using DNA Metabarcoding

The decomposition of animal bodies is a process defined by specific stages, described by the state of the body and participation of certain guilds of invertebrates and microorganisms. While the participation of invertebrates in decomposing is well-studied and actively used in crime scene investigations, information on bacteria and fungi from the scene is rarely collected or used in the identification of important factors such as estimated time of death. Modern molecular techniques such as DNA metabarcoding allow the identification and quantification of the composition of microbial communities. In this study, we used DNA metabarcoding to monitor fungal succession during the decomposition of juvenile pigs in grasslands of New Jersey, USA. Our findings show that decomposition stages differ in a diversity of fungal communities. In particular, we noted increased fungal species richness in the more advanced stages of decomposition (e.g., bloat and decay stages), with unique fungal taxa becoming active with the progression of decay. Overall, our findings improve knowledge of how fungi contribute to forensically relevant decomposition and could help with the assessment of crime scenes.

A Summary of Concepts, Procedures and Techniques Used by Forensic Entomologists and Proxies

Forensic entomology is a branch of forensic science that incorporates insects as a part of solving crime. Insect-based evidence recovered at a crime scene can be used to estimate the minimum postmortem interval, determine if a carcass/corpse has been relocated, and contribute to the cause and manner of death. The current review summarises the stepwise usage of forensic entomology methods at a crime scene and in the laboratory, including specimen collection and rearing, identification, xenobiotic detection, documentation, and referencing previous research and casework. It also provides three standards for the collection of insects when attending a crime scene. The Gold standard attributes to a forensic entomologist (FE) who is likely to be well-trained attending a scene. The subsequent standards (Silver and Bronze) have been added because the authors believe that this information is currently missing in the literature. The purpose is so that an attending crime scene agent/proxy with some basic knowledge and some simple tools can recover almost all the insect information required by an FE to make the best estimation of the minimum postmortem interval.

Effect of diazinon (organophosphate) on the composition and succession of Calliphoridae assemblages in rabbit carcasses in the Eastern Amazon

Fatal poisonings with diazinon may occur both accidentally or intentionally in suicide cases. Forensic entomotoxicology can aid in understanding these deaths by detecting and analyzing the interference of toxic substances in the biology of necrophagous insects. Hence, this study sought to evaluate diazinon's effect on the composition and succession of calliphorid species in the tropical savannas of the Amazon. Nine rabbit carcasses were divided into three groups: one control and two diazinon treatments (100 mg/kg and 300 mg/kg); each group had three replicates. Three fragments of the Amazon tropical savanna were selected for the experiments. Daily collections of adult and immature calliphorids were performed. Five decomposition stages were observed: fresh, bloated, active decay co-occurring, advanced decay, and dry. Eight species of Calliphoridae were identified among the collected adults: Chloroprocta idioidea (0.1%), Chrysomya albiceps (58.3%), Chrysomya megacephala (14.2%), Chrysomya putoria (2.6%), Cochliomyia hominivorax (1.3%), Cochliomyia macellaria (0.5%), Lucilia eximia (19.8%), and Paralucilia paraensis (3.3%). The adult specimens in the control group with the highest abundance were observed only from the advanced decay stage onward. In the dry stage, abundance was higher in control than in treated carcasses. From the sampled 941 Calliphorid immatures, three species were identified: C. albiceps (76,3%), C. putoria (1%), and L. eximia (22,7). The number of immatures was higher in control than in treated carcasses. Therefore, diazinon interferes with the putrefaction timeframe in carcasses, slowing the decomposition stages and affecting their colonization by immature forms of Calliphoridae.

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.

Detection of terbufos in cases of intoxication by means of entomotoxicological analysis using ATR-FTIR spectroscopy combined with chemometrics

The detection of toxic substances in larvae from carcasses in an advanced stage of decomposition may help criminal expertise in elucidating the cause of death in suspected cases of poisoning. Terbufos (Counter®) or O,O-diethyl-S-[(tert-butylsulfanyl)methyl] phosphorodithioate is an insecticide and systemic nematicide, which has very high toxicity from an acute point of view (oral LD₅₀ in rodents ranging from 1.4 to 9.2 mg/kg) that has been marketed irregularly and indiscriminately in Brazil as a rodenticide, often being used to practice homicides. The present study aims to evaluate the use of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy to detect traces of terbufos pesticide in fly larvae (Sarcophagidae). ATR-FTIR spectra of scavenger fly larvae from control (n = 31) and intoxicated (n = 80) groups were collected and submitted to chemometric analysis by means of multivariate classification using principal component analysis with quadratic discriminant analysis (PCA-QDA), successive projections algorithm with quadratic discriminant analysis (SPA-QDA) and genetic algorithm with quadratic discriminant analysis (GA-QDA) in order to distinguish between control and intoxicated groups. All discriminant models showed sensitivity and specificity above 90%, with the GA-QDA model showing the best performance with 98.9% sensitivity and specificity. The proposed methodology proved to be sensitive and promising for the detection of terbufos in scavenger fly larvae from intoxicated rat carcasses. In addition, the non-destructive nature of the ATR-FTIR technique may be useful in preserving the forensic evidence, meeting the precepts of the chain of custody and allowing for counter-proof.

Impact of using Sarcophaga (Liopygia) argyrostoma (Robineau-Desvoidy, 1830) as a toxicological sample in detecting clonazepam for forensic investigation

Background

Sarcophagidae along with Calliphoridae (superfamily Oestroidea) were known as important colonizers of cadavers and could be used to estimate the postmortem interval (PMI), through tracking the flies colonizing pattern and/or monitoring their growth rates on cadavers. Many previous researches discussed the impact of toxins in decomposing corpses, on the developmental stages of insects, which would affect the accuracy of PMI estimation. Clonazepam belongs to the benzodiazepines, and it is one of the most routinely used drugs to control humans’ seizures. The current study aimed to investigate the effect of clonazepam on the developmental stages of Sarcophaga argyrostoma, one of the most widespread Sarcophagidae in Giza Governorate. Also, we investigate the ability of these developmental stages to detect the drug.

Results

The current study used different concentrations of clonazepam (25, 50, and 100 mg/ml) as an in vitro application of the flesh fly S. argyrostoma. The drug has affected significantly the morphological measurements (weight, length, and width) of the different developmental stages, especially in the highest concentration (100 mg/ml). Quantitative and qualitative analyses were applied, by using high-performance liquid chromatography-mass spectrometry (HPLC–MS) and protein carbonyls amount respectively, to detect clonazepam in the second, early third, and late third larval instars and prepupa of S. argyrostoma. The results showed that the relationship between the concentration of the drug and its detection in the same developing instar is interdependent, using HPLC–MS. However, the drug faded from instar to the following one and transformed to its metabolite form. Measuring the protein carbonyls amount (OD/mg protein/min) revealed an elevation in the macromolecules damage, compared to the control groups, in almost all treated groups.

Conclusions

The current data suggested that clonazepam has oxidative damage in S. argyrostoma. While HPLC–MS was efficient in measuring the concentration of the drug in the insect, protein carbonyls analysis was a time- and cost-saving method and could be used to detect the drug in insects qualitatively.

Graphical abstract

Biological Response of Chrysomya putoria (Wiedemann, 1818) (Diptera: Calliphoridae) Pupae After Submersion in Freshwater

Forensic Entomology uses arthropods to aid in legal investigations. This study checked the biological response of Chrysomya putoria pupae to submersion in fresh water for up to 6 d, evaluating the critical submersion time, survival rate, and development time of the flies. Adults were collected using fish baits in two typical traps. Seven hundred and twenty fourth-generation pupae with 2 d of development were used and separated into submergence intervals: 24, 48, 72, 96, 120, and 144 h. An additional 120 pupae were used as a control. Each treatment was done in triplicate, consisting of 40 pupae distributed in four tulle-sealed test tubes containing 10 pupae each. All tubes of each treatment were co-adhered in test tube racks and were submerged in mineral water in a container with constant oxygenation, except those of the control group, which were not submerged. The tubes were removed from the water according to their respective submersion interval, until 144 h was completed. The control group had a survival rate of 90%, while the 24-h treatment had 85% and the 48-h treatment had 35.8%. The critical submersion time for pupae was 72 h, with 100% mortality by 144 h. The average development time for the control group was 3.2 d, while the 24- and 48-h treatments developed in 4.3 and 6.3 d, respectively. The longer the individuals were submerged, the lower the survival rate was, while the development time increased. The data obtained in this study have potential in applications to estimate the interval of submersion of a cadaver.

The Effects of Gunshot Residue Components (Pb, Ba, and Sb) on the Life History Traits of Lucilia sericata (Diptera: Calliphoridae)

The present study aimed to investigate the impact of gunshot residue (GSR) components (Pb, Sb, and Ba) on the life history parameters of Lucilia sericata (Meigen, 1826) (Diptera: Calliphoridae). This experiment was carried out at the Zoology Department, the Ondokuz Mayıs University in 2020. About 50 larvae, respectively were exposed to the chicken liver with four different concentrations of GSR particles and life history parameters recorded. A two-way analysis of variance (Two way ANOVA) was used on the larval weight, and length, development time, percentage of pupal and larval survival. Pearson's correlation coefficient was used to assess the association between life-history parameters and the concentration of GSR. The total development times decreased with increasing Sb, Ba, and Pb concentrations in the diets 1-3 d when compared to the control The results showed that Ba and Sb significantly decreased larval and pupal survival and GSR decreased the pupa and adult weight as compared to the control. We concluded that life-history parameters of L. sericata are sensitive to GSR residue and heavy metal changes in the environment. The presence of gunshot residue in the corpse should be kept in mind in a criminal investigation.

Effect of Zolpidem Tartrate on the Developmental Rate of Forensically Important Flies Chrysomya megacephala (Diptera: Calliphoridae) and Chrysomya saffranea

Entomotoxicology is an emerging science in the forensic investigation of death; it now influences judicial activities. Briefly, carrion flies ingest various chemicals as they feed on a cadaver. In entomotoxicology, such toxicological compounds are qualitatively and quantitatively analyzed in insects recovered from carrion. Some of these chemicals can disrupt flies' cellular physiology, leading to acceleration or delay in their developmental rate. In this study, the effect of zolpidem-contaminated tissue on the dipteran flies Chrysomya megacephala (Fabricius 1794) and Chrysomya saffranea (Bigot 1877) was assessed. Zolpidem tartrate is a sedative-hypnotic compound commonly used to treat anxiety and sleeping disorders, but it is associated with death from suicide. The effects were tested by providing the flies with liver tissue treated with various concentrations of zolpidem tartrate. The morphological parameters and development rate for all life cycle stages of treated insects were determined and used to estimate postmortem intervals. Results showed that the morphological parameters, i.e., weight, width, and length and rate of development of C. megacephala and C. saffranea was negatively associated with zolpidem tartrate concentration of C. saffranea, were negatively associated with the concentration of zolpidem tartrate, indicating that arthropod evidence evaluation can help establish the cause and time of death.

It is all about the insects: a retrospective on 20 years of forensic entomology highlights the importance of insects in legal investigations

This study highlights the importance of insect evidence by evaluating 949 insect-associated cases, including 139 entomological reports, from 2001 to 2019 at the Institute of Legal Medicine Frankfurt/Germany. With a high number of cases in the summer months and a low number in the colder season, 78.5% of the bodies were found indoors, regardless of year or month. In more than 80% of the cases, where PMI information was available (n = 704), the presumed PMI ranged from 1 to 21 days, a period during which entomological evidence can provide a day-specific estimate of PMI_min. In cases where insects have been identified to species level (n = 279), most bodies were infested by one or two species with a maximum of 10 different species. Overall, a total of 55 insect species were found. Information on biology, activity and distribution of the most abundant taxa is given and applied for 5 case histories estimating different PMI_mins of up to over 6 months. Despite proved importance and scientific development of forensic entomology, insects are still rarely considered as a tool in forensic case work. The main reasons are a lack of awareness and (too) late involvement of a forensic entomologist. Our work shows that forensic entomology is an independent discipline that requires specialist expertise.

Infrared spectroscopy and forensic entomology: Can this union work? A literature review

For more than two decades, infrared spectroscopy techniques combined with multivariate analysis have been efficiently applied in several entomological fields, such as Taxonomy and Toxicology. However, little is known about its use and applicability in Forensic entomology (FE) field, with vibrational techniques such as Near-infrared spectroscopy (NIRS) and Medium-infrared spectroscopy (MIRS) underutilized in forensic sciences. Thus, this work describes the potential of NIRS, MIRS, and other spectroscopic methodologies, for entomological analysis in FE, as well as discusses its future uses for criminal or civil investigations. After a thorough research on scientific journals database, a total of 33 publications were found in scientific journals, with direct or indirect application to FE, including experimental applications of NIRS and MIRS in taxonomic discrimination of species, larval age prediction, detection of toxic substances in insects from environments or crime scenes, and detection of internal or external infestations by live or dead insects in stored products. Besides, NIRS and MIRS combined with multivariate analysis were efficient, inexpensive, fast, and non-destructive analytical tools. However, more than 51% of the spectroscopic publications are concentrated in the stored products field, and so we discuss the need for expansion and more direct application in other FE areas. We hope the number of articles continues to increase, and as NIRS and MIRS technology progress, they advance in forensic research and routine use.

Effects of antibiotics ceftriaxone and levofloxacin on the growth of Calliphora vomitoria L. (Diptera: Calliphoridae) and effects on the determination of the post-mortem interval

The determination of the post-mortem interval (PMI) is one of the main tasks of forensic entomology, where growth and stages of development of arthropods are used for PMI determination. It is well acknowledged that maggot development is significantly influenced by temperature. Attention has also been paid to the microbial populations of the cadaver, because toxic substances contained in the substrate can influence the microorganisms and affect arthropods growth and development. However, little is known about the influence of antibiotics taken during lifetime of a person on insect development after that persons death. The aim of this study was to test the hypothesis that the antibiotics ceftriaxone and levofloxacin cause inhibition of growth and delay of pupation of the blow fly Calliphora vomitoria, which would then lead to an incorrect determination of the post-mortem interval in forensic cases. It was found that maggot development was delayed by levofloxacin mixed in minced pork, where a mixture of both antibiotics increased this effect. The maggot growth in the samples with ceftriaxone was not delayed. Pupation was delayed in treatments with a mixture of both antibiotics. The mortality was reduced by separate or combined application of ceftriaxone and levofloxacin, which we attribute to a bactericidal effect of the antibiotics on maggot pathogens. Depending on the concentration of the antibiotics, an underestimation of the post-mortem interval between 24 and 48 h could be suspected. We conclude that antibiotics need to be considered if instar stages are to be used to determine the PMI and that some antibiotics may improve the breeding conditions of maggots.

Effect of Terbufos (Organophosphate) on the Cadaveric Colonization Process: Implications for Postmortem Interval Calculation

The determination of necrophagous fly specie's development time is considered an accurate method for estimating postmortem interval (PMI). However, pesticides and other chemicals can alter the flies' life cycle, inducing errors in PMI estimation. Thus, this work aimed to evaluate the effect of different doses of Terbufos (Organophosphates) on the temporal dispersion pattern and development of immature dipterans associated with decaying rat carcasses. For this, 150 g female Wistar rats received, via gavage, 200 µl of Terbufos (5 or 10 mg/kg) or distilled water (control) and, after 30 min of administration, the animals were euthanized and distributed in suspended traps to decompose under environmental conditions. The dispersing immatures were collected daily, and their development time was monitored until the emergence of adult flies. After data analysis, it was observed that Terbufos altered 1) the temporal pattern of larval dispersion; 2) the composition and structure of the colonizing assemblage (emerged adults); 3) species' development time, accelerating or delaying their cycle, depending on the dose used; and 4) the califorids and sarcophagids emergence rate, increasing the mortality of pupae from intoxicated carcasses. Thus, this work demonstrates experimentally that Terbufos directly influences the development of flies with forensic potential and discusses the implications for PMI estimation, which can assist in future investigative processes with suspected poisoning by this organophosphate.

Comparison of Accumulated Degree-Days and Entomological Approaches in Post Mortem Interval Estimation

Simple Summary

Among the investigative questions to define the temporal frame of a criminal event, the time since death plays a fundamental role. After death, the body goes through a series of physical and chemical transformations—known as decomposition. The way in which different parts of the body undergo these transformations can be quantified with a scale of scores (TBS, the total body score) and used for the time since death evaluation using the accumulated degree-days (ADDs) parameter, which accounts for time and temperature. This method is reported as TBS/ADD. Another way to estimate the time since death is based on the insect development on the body. Flies represent the first body coloniser and the development of their immature stages is used to define the time of colonisation that is temperature dependent and species specific. In this study, the two methods were compared based on 30 forensic cases occurring in northern Italy. The results highlighted the limits of the TBS/ADD method and the importance of the entomological approach, keeping in mind that with insects the colonization time is evaluated. This time is the minimum time since death.

Abstract

Establishing the post mortem interval (PMI) is a key component of every medicolegal death investigation. Several methods based on different approaches have been suggested to perform this estimation. Among them, two methods based their evaluation on the effect of the temperature and time on the considered parameters: total body score (TBS)/accumulated degree-days (ADDs) and insect development. In this work, the two methods were compared using the results of minPMI and PMI estimates of 30 forensic cases occurring in northern Italy. Species in the family Calliphoridae (Lucilia sericata, Calliphora vomitoria and Chrysomya albiceps) were considered in the analyses. The results highlighted the limits of the TBS/ADD method and the importance of the entomological approach, keeping in mind that the minPMI is evaluated. Due to the fact that the majority of the cases occurred in indoor conditions, further research must also be conducted on the different taxa to verify the possibility of increasing the accuracy of the minPIM estimation based on the entomological approach.

Seasonal Impact of Heroin on Rabbit Carcass Decomposition and Insect Succession

This study investigates the succession of insects and the length of the decomposition of rabbit carcasses injected with heroin. In total, 24 rabbits (2-2.5 kg, Oryctolagus cuniculus domesticus L.) were used in the study. Twelve carcasses were exposed to insect activity in winter (January and February) and 12 in summer (July and August) in Riyadh, Saudi Arabia. Three replicate experiments were conducted in each season. For each experiment, three rabbits were injected with varying doses of heroin, and the fourth rabbit was used as a control, being injected only with saline solution. Insects belonging to the order Diptera, Coleoptera, and Hymenoptera were attracted to the carcasses. In both of the investigated seasons, heroin appeared to delay the decomposition process but did not have a significant impact on the number of insects. In general, the number of flies in both seasons was substantially higher than that of beetles and ants. During the summer, flies were more attracted to treated carcasses with a higher dose of heroin. Some flies such as Musca domestica L. (Diptera: Muscidae) and Chrysomya albiceps Wiedemann (Diptera: Calliphoridae) and some beetles such as Pimelia boyeri Solier (Coleoptera: Tenebrionidae) were represented on the carcasses by different developmental instars (larvae, pupae, and adults). Overall, heroin has not potential effects on the insect succession patterns of insect, however, influences the decomposition of rabbit carcasses. These findings are important while using insects in medicolegal investigation, since heroin is one of the common poisons used as an addictive agent.

Lead toxicity in Lucilia cuprina and electrochemical analysis: a simple and low-cost alternative for forensic investigation

Entomotoxicology allows the detection and analysis of substances such as poisons, drugs, and metals in necrophagous insects using analytical protocols. In a forensic situation related to death by gunshot, the gunshot residue (GSR) is dispersed at the crime scene and may be consumed by necrophagous insects. Lead (Pb) is the most abundant metal in GSR samples and it can be determined using non-portable methods. However, the toxicity effects of GSR samples on Lucilia cuprina (Diptera: Calliphoridae) and the detection of Pb via portable electrochemical methods have not been investigated. This study describes for the first time the toxicity analysis of Pb on immature L. cuprina through their survival rate and influence of Pb on immature development. In addition, the bioaccumulation of Pb in the larvae samples was determined based on square wave anodic stripping voltammetry (SWASV) measurements. The results revealed a low limit of detection to Pb (6.5 μg L^-1) and the analytical performance was satisfactory because it measures Pb levels in larvae exposed to a diet containing 50 μg Pb g^-1. Furthermore, the levels of Pb influenced the survival rate and development time of the immature L. cuprina. Larvae exposed to a high concentration of the metal (50 μg Pb g ^-1) showed statistically significant changes (p < 0.05). The presence of Pb in immature L. cuprina can be used to estimate the post-mortem interval; thus, the present study provides important information in forensic entomology.

Impacts of antemortem ingestion of alcoholic beverages on insect successional patterns

This paper studies the impacts of antemortem ingestion of alcoholic beverages by the domestic rabbit, Oryctolagus cuniculus L., on postmortem successional patterns of insects during winter and summer 2018 in Riyadh, Saudi Arabia. Insect samples were collected from the carcasses of rabbits fed alcoholic beverages as well as untreated rabbits for 15 days postmortem during two successional studies in each season. The results showed that, during both seasons, the decomposition process for the carcasses of rabbits fed alcoholic beverages antemortem was one to two days longer. The results also showed, however, that alcoholic beverages did not affect insect succession patterns in either season. In fact, the number of insects appeared to be influenced by the ambient temperature during the two seasons, with 4415 insects in the winter compared to 1033 insects in the summer. In total, 30 insect taxa were collected during the winter study from the carcasses of rabbits fed alcoholic beverages antemortem; while 26 of these same taxa were collected from the carcasses of the untreated rabbits. Among the treated rabbits, those fed 25 ml alcoholic beverages treated attracted the highest number of insect taxa (24 taxa). In the summer study, 21 insect taxa were collected in total, 19 from the carcasses of the alcohol-treated rabbits and 13 from untreated rabbits. Among the treated rabbits, those fed 50 ml alcoholic beverages attracted the highest number of insect taxa (14 taxa). These results contribute to the understanding of the factors affecting the use of insects in medical investigations, given that alcoholic beverages are a common addictive agent.

Carrion decomposition and assemblage of necrophagous dipterans associated with Terbufos (Organophosphate) intoxicated rat carcasses

Organophosphate use represents one of the main causes of intentional and accidental poisoning in Brazil. Because they induce alteration in carcass decomposition and succession of necrophagous Diptera, they are important investigative tool in forensic entomology for determining the postmortem interval (PMI) and cause of death. Thus, this work aimed to evaluate the influence of Terbufos, the most commonly used organophosphate for suicides in Rio Grande do Norte, Brazil, in the decomposition process and necrophagous fly assemblies in intoxicated rat carcasses. For this, 150g female Wistar rats received, by gavage, 200µL of Terbufos (5mg/kg or 10mg/kg) or distilled water (control). Approximately 30 minutes after administration, animals were euthanized and distributed in suspended traps to decompose under environmental conditions. Decomposition was monitored daily, with photographic record and collection of the visiting dipterofauna until the dry phase. Data show that the higher dose of Terbufos i) accelerates carcass decomposition in 24h; ii) decreases the species richness and abundance of scavengers flies when compared to the control; iii) changes the succession pattern, delaying the arrival of important species for the PMI estimate and iv) causes 8% mortality of the visiting dipterofauna. This work provides relevant information about dipteran assemblages and changes in the cadaver decomposition process associated with Terbufos intoxication, which may assist in future investigative processes with suspected organophosphate poisoning.

Evaluation of activities of dipteran maggots on a poisoned pig cadaver at Nnamdi Azikiwe University Awka, Nigeria

Background

Forensic entomology is evolving into entomotoxicology, which is a critical approach in forensic toxicology that alternatively assesses presence of toxins in insects that have eaten a decomposing cadaver. Toxic substances in or on a dead body may accumulate in the tissues of fly maggots while feeding on the body and thus may alter their developmental rate. Thus, four out of eight healthy pigs (Sus scrofa Linn.) that weighed on the average 22.3 ± 1.9 kg were sacrificed with zinc phosphide as food poison, while the remaining four pigs were sacrificed by strangulation during the rainy and dry seasons of 2014 and 2015 respectively. Their bodies were deposited in a building to mimic indoor decomposition. The building is on 6° 15′ 18.06″ N and 7° 06′ 41.37″ E at Nnamdi Azikiwe University Awka, Anambra State, Nigeria. The effect of the zinc phosphide on the decomposition duration of the cadavers was monitored. Toxicological assessment of zinc and phosphorus on maggots found on the cadavers was performed with an atomic absorption spectrophotometer.

Findings

The zinc phosphide did not affect the decomposition duration of the cadaver and did not prolong or shortened the life cycle of the fly maggots when compared with the control (strangled pig cadaver). For the poisoned cadavers, the atomic absorption spectrophotometer detected zinc in the maggot tissues collected from them while phosphorus was not detected. Neither zinc nor phosphorus was detected in the maggot tissues collected from the strangled cadavers.

Conclusions

The study showed that the zinc component in the zinc phosphide commonly used as rodenticide in Awka can be detected in maggots collected from such a suspected poisoned cadaver. Other implications related to toxicological studies on cadaveric insects in forensic entomology and serving as alternative matrices in forensic toxicology in any questionable death were also highlighted.

The implication of morphometrics and growth rate of dipteran flies in forensic entomotoxicology research: a review

Forensic entomotoxicology integrates toxicology into forensic entomology to estimate minimum postmortem interval (PMI_min) and circumstances of death where toxicants and poisonous substances are the suspected cause of death. Forensic entomotoxicology not only confirms the presence of toxicants in insects feeding off a cadaver but also studies its effect on the bio-morphometry and growth rate of insects. This review article highlights the effects of various toxicants on forensically important species of dipteran flies. It also discusses the parameters that may affect accuracy in estimation of time since death. The bio-physical effects of toxicants (excluding the analytical approach for qualitative detection) would help understand the trends in forensic entomotoxicological research worldwide.

Genetic diversity of Calliphora vicina (Diptera: Calliphoridae) in the Iberian Peninsula based on cox1, 16S and ITS2 sequences

The study of Diptera at the scene of a crime can provide essential information for the interpretation of evidence. Phylogeographic reconstruction could help differentiate haplotypes of a dipteran species in a geographical area, clarifying, for example, the details of a possible relocation of a corpse. In addition, inferring the ancestral areas of distribution helps to understand the current status of the species and its biogeographic history. One of the most important species in forensic entomology is Calliphora vicina Rovineau-Desvoidy, 1830 (Diptera: Calliphoridae). The aim of this work is to increase our knowledge of this species in the Iberian Peninsula using 464 specimens from Spain and Portugal. These samples were identified using morphological keys and by molecular methods using fragments of the cox1, 16S and ITS2 genes. The phylogeographic history of these populations was inferred from haplotype networks and the reconstruction of ancestral areas of distribution. The molecular results corroborated the morphological identifications of the samples. Phylogeographic networks showed no geographical structure, as haplotypes are shared among almost all populations. reconstruct ancestral state in phylogenies analyses showed a high rate of movement among populations, possibly related to human activity. These results suggest that this species had a very rapid and recent spatial and demographic expansion throughout the Iberian Peninsula.

Revisiting the concept of entomotoxicology

Until now, the term entomotoxicology has only been used in medico-legal sciences. However, entomotoxicology as a whole has a much wider scope and forensic entomotoxicology is just one of its branches. Based on the literature a wider definition of the term is presented. Today, we can distinguish two major branches of entomotoxicology: 1) Forensic entomotoxicology, which uses the insects as evidence of the presence of xenobiotics in decomposing tissue during an investigation and 2) Environmental entomotoxicology, which uses the insects as bioindicators of environmental pollution in non-criminal circumstances. While forensic entomotoxicology is a relatively new discipline, research in environmental entomotoxicology began as far back as the 1920s. A review of the work in entomotoxicology from the last 6 years is presented, covering several interesting new trends. This article aims to redefine entomotoxicology, which should increase awareness to bring more collaborations and multidisciplinary between related scientific fields.

The Succession of Flies of Forensic Importance Is Influenced by Volatiles Organic Compounds Emitted During the First Hours of Decomposition of Chicken Remains

After death, a series of primary reactions occur that produce volatile organic compounds (VOCs) that are released into the environment. In this study, we investigated if the succession of flies of forensic importance in the first hours after death is mediated by VOCs in order to better understanding of the ecology of necrophagous insects. In total, 685 adult insects (Diptera and Hymenoptera) were collected by traps baited with chicken remains at different decomposition times (0, 6, 12, 24, 36, or 48 h). Of the total of insects caught, individuals from six families of Diptera can be cataloged of forensic importance. The most abundant dipteran family was Piophilidae with 213 individuals, followed by Calliphoridae with 178 specimens. Of the total flies caught, 90% were females and the rest were males. Most of the caught females were categorized as gravid, which visited more often the decaying tissues compared to nongravid females. The abundance of the flies increased in the remains with a longer time of decomposition. Six VOCs emitted in different relative quantities were identified according to the decomposition time of the remains. An apparent association was observed between the emission of ρ-cresol with Lucilia eximia (Wiedemann), between the emission of phenol, dimethyl disulfide, and dimethyl trisulfide with Chrysomya rufifacies (Macquart), and between the emissions of indole with Cochliomyia macellaria (Fabricius).

Detection of Pb, Ba, and Sb in Cadaveric Maggots and Pupae by ICP-MS

The concentrations of lead (Pb), barium (Ba), and antimony (Sb), characteristic of GSR, were determined in soil sediments and immature (larvae) of cadaveric flies of the family Calliphoridae, by inductively coupled plasma mass spectrometry (ICP-MS). This research refers to a case study from two real crime scenes in which the corpses were in an advanced state of decomposition. In case 1, the victim had holes similar to gunshot wounds, and in case 2, there was no evidence of perforations in the corpse. Soil sediment collection was performed at three different points of the terrain, at a minimum distance of 10 m from the corpse, for cases 1 and 2. In relation to the collection of immatures, larvae were collected in regions of the mouth, nose, and orifices similar to the entry of firearms projectile into the body, for case 1, and collection of larvae and pupae, located on the body and underneath it, for case 2. It was possible to detect and quantify the three elements of interest (Pb, Ba, and Sb) by ICP-MS in both sediment and cadaveric larvae. Concentrations of 4.44, 8.74, and 0.08 μg/g were obtained for Pb, Ba, and Sb, respectively, in the soil for case 1. For the case 2, the concentrations in Pb, Ba, and Sb were from 16.34 to 26.02 μg/g; from 32.64 to 57.97 μg/g and from 0.042 to 0.30 μg/g, respectively. In the larvae, Pb, Ba, and Sb were quantified in cases 1 and 2 with a concentration of 6.28 and 1.78 μg/g for Pb, 1.49 and 2.94 μg/g for Ba, 0.50 μg/g and <LD for Sb, respectively. These new results present the detection of characteristic elements of GSR in cadaveric larvae in humans in a real crime scene, besides highlighting the importance of the study of immature flies, using the ICP-MS technique in forensic analysis.

Detection of benzodiazepines in decomposing rabbit tissues and certain necrophagic dipteran species of forensic importance

The determination of benzodiazepines (carbamazepine and clobazam) in rabbit carcass tissues and larvae of three Calliphorid flies is described. After feeding the rabbits with lethal and toxic doses, samples of larvae and carcass tissues were studied. Residual drugs were determined using Ultra-high-performance liquid chromatography – quadrupole time-of-flight mass spectrometry (UHPLC/QTOF-MS). Benzodiazepines and its main active metabolites have been detected in the rabbit tissues at different retention times depending on the dosage used (lethal or toxic). A total of 1150 insects were collected and 800 larvae of the flies Chrysomya albiceps, Lucilia sericata and L. silvarum were used in the analysis. The presence of benzodiazepines in the rabbit tissues has been shown to typically affect the larval development cycle of the three necrophagous flies. Chrysomya albiceps larvae feed on drugs developed faster, while the development of L. sericata and L. silvarum larvae slowed. These results indicate that drugs have an impact on the life cycles of insects, which suggests that the presence of these substances is a factor that needs to be taken into account when estimating the post-mortem interval (PMI).

Characterization and Identification of Puparia of Hydrotaea Robineau-Desvoidy, 1830 (Diptera: Muscidae) From Forensic and Archaeological Contexts

Flies and beetles are the main components of the entomofauna colonizing a body after death. Following the recognition of constant and predictable colonization patterns and the knowledge about the dependence of the insect development to temperature, a new discipline, forensic entomology, has provided information useful to reconstruct criminal events. Funerary archaeoentomology has also applied the same rationale in archaeological contexts. Puparia represent a large fraction of the insect remains that can be found associated with a cadaver, especially when the body is mummified or in the advanced stages of decomposition. Puparium identification is still a problematic topic due to the lack of identification keys and, in several cases, a lack of diagnostic feature descriptions. Here, we focus the attention on some Hydrotaea Robineau-Desvoidy (Diptera, Muscidae) puparia from forensic and archaeological contexts. Puparia of Hydrotaea capensis (Wiedemann), Hydrotaea ignava (Harris), Hydrotaea aenescens (Wiedemann), Hydrotaea similis Meade, Hydrotaea pilipes Stein, and Hydrotaea dentipes (Fabricius) are here detailed and illustrated. Posterior spiracles, anal plate, and intersegmental spines have been considered as good diagnostic characters for the identification of these puparia.

Development and validation of an HPLC-MS/MS method for the detection of ketamine in Calliphora vomitoria (L.) (Diptera: Calliphoridae)

Entomotoxicology is a branch of forensic entomology that studies the detection of drugs or other toxic substances from insects developing on the decomposing tissues of a human corpse or animal carcass. Entomotoxicology also investigates the effects of these substances on insect development, survival and morphology to provide an estimation of the minimum time since death. Ketamine is a medication mainly used for starting and maintaining anesthesia. In recent years ketamine has also been used as a recreational drug, and occasionally as a sedating drug to facilitate sexual assault. In both activities, it has resulted in several deaths. Furthermore, ketamine has been also implicated in suspicious deaths of animals. The present research describes for the first time the development and validation of an analytical method suited to detect ketamine in larvae, pupae, empty puparia, and adults of Calliphora vomitoria L. (Diptera: Calliphoridae), using liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). This research also considers the effects of ketamine on the survival, developmental rate and morphology (length and width of larvae and pupae) of C. vomitoria. The larvae were reared on liver substrates homogeneously spiked with ketamine concentrations consistent with those found in humans after recreational use (300 ng/mg) or allegedly indicated as capable of causing death in either humans or animals (600 ng/mg). The results demonstrated that (a) HPLC-MS/MS method is applicable to ketamine detection in C. vomitoria immatures, not adults; (b) the presence of ketamine at either concentration in the food substrate significantly delays the developmental time to pupal and adult instar; (d) the survival of C. vomitoria is negatively affected by the presence of ketamine in the substrate; (e) the length and width of larvae and pupae exposed to either ketamine concentration were significantly larger than the control samples.

Rapid molecular identification of necrophagous diptera by means of variable-length intron sequences in the wingless gene

The arrival of arthropods at a corpse exhibits specific temporal patterns, and Diptera play a key role in the initial stages of the decomposition process. Thus, the correct species assignment of the insect larvae found on a decomposing body is an important step in forensic investigations. Here, we describe a molecular procedure to define the species at larval age found on a corpse more quickly and easily than current systems. Our method involves a unique PCR amplification of a DNA segment within the evolutionarily conserved wingless gene, involved in embryo development. The amplified DNA segment contains the fourth intron of wingless, which we found to be variable in length, from about 800 to 3000 bp, among species of necrophagous Diptera. The identification of the amplified segment size in species from Lucilia, Calliphora and Sarcophaga genera, allowed us to determine the species at larval age collected in the early stages of a decomposing body, with a simple PCR amplification and subsequent electrophoresis. This procedure may help in forensic investigations to estimate the minimum Post Mortem Interval (PMI-min) of a body colonized by these larvae, avoiding the use of time-consuming and/or more expensive procedures.

Analysis of the Effect of Cyclophosphamide and Methotrexate on Chrysomya megacephala (Diptera: Calliphoridae)

Forensic entomotoxicology investigates the effects of chemical substances in the development of scavenger insects and the reflection on estimating the minimum postmortem interval (PMI). To evaluate the impact of the chemotherapeutic drugs cyclophosphamide (CF) and methotrexate (MTX) on the postembryonic development of Chrysomya megacephala, controlled experiments were performed by rearing the larvae on spiked minced beef with different concentrations of these drugs. The results indicated that CF significantly decreased their developmental rate up to 28 h but had no significant effect on larval and adult sizes, survival rate, and sex ratio, whereas MTX decreased larval and adult sizes, survival rate, and there was a deviation in the expected sex ratio toward females in MTX-exposed larvae but had no significant impact on developmental rate. These negative interference factors should be considered in cases of suspected death of people that have undergone chemotherapy.

Species diversity and tissue specific dispersal of necrophagous Diptera on human bodies

In forensic entomology, many studies analyze fly activity and succession on dead bodies by using pig cadavers and a variety of small baited traps. Data on real human bodies are very rare. To address this shortcoming, we analyzed the fly fauna of 51 human bodies in Germany. Sex, age, place of discovery, and presumed time of death were noted. Larvae were sampled during autopsy according to body region or tissue. For every infested region, the total number of fly larvae were estimated and classified into categories of 1-10, 11-50, and 50+. All samples were identified to the species level. Besides a descriptive analysis of their occurrence patterns, a categorical PCA was performed, and multispecies generalized linear models and a latent variable model were run. Our results highlight the most forensically important blow flies on human bodies in Central Europe (Lucilia sericata, L. ampullacea, Phormia regina, Calliphora vicina); prove, for the first time, the general transferability of species lists based on succession studies on pig cadavers; recommend a certain set of species, such as the so-far neglected L. ampullacea, for future developmental studies; and reveal competitive occurrence of up to six species on the same body as a potential factor of influence. Assignment to a certain body region was often possible and our data clearly indicate certain tissues, e.g. brain, as of high interest for future developmental studies. Focusing on real scenario settings helps direct research to forensically relevant questions and appraises the plausibility of vital laboratory studies.

Dipteran Diversity and Ecological Succession on Dead Pigs in Contrasting Mountain Habitats of Chiapas, Mexico

A comparative study of Diptera communities associated with pig carcasses was carried out in urban and natural settings in tropical mountain habitats of Southern Mexico. Schoenly-type traps were used to set out pig carcasses during 68 d of sampling effort. In total, 1,703 adult Diptera specimens were collected in both localities combined, and recording a total of 30 (morpho) species and 19 families. Compared to natural habitats, a significantly greater diversity in urban habitats, as well as a faster decomposition process of carcasses, was detected. Significant differences were also detected for the composition and structure of Dipteran communities between urban and natural sites. Dominant species of Calliphoridae for natural and urban habitats were represented by Compsomyiops spp. and Cochliomyia macellaria (Fabricius; Diptera: Calliphoridae), respectively. The properties of indicator species for urban and natural sites are discussed. Twenty Dipteran species were significantly associated to different decomposition stages. Such affinity would allow for estimating the post-mortem interval (PMI) in comparable situations.

Development and Validation of a Method for the Detection of α- and β-Endosulfan (Organochlorine Insecticide) in Calliphora vomitoria (Diptera: Calliphoridae)

Entomotoxicology studies employ analytical methods and instrumentation to detect chemical substances in carrion insects feeding from the decomposing tissues. The identification of such chemicals may determine the cause of death and may be used for the estimation of the minimum time since death. To date, the main focus of entomotoxicological studies has been the detection of drugs, whereas little information concerns the effects of pesticides on blowflies. Pesticides are generally freely available and more affordable than drugs but they can also be a home hazard and an accessible candidate poison at a crime scene. A QuEChERS extraction method followed by Gas chromatography-mass spectrometry (GC-MS) analysis was developed for the detection of α- and β-endosulfan (organochlorine insecticide and acaricide) in Calliphora vomitoria L. (Diptera: Calliphoridae) and validated. Furthermore, the effects of endosulfan on the morphology, development time and survival of the immature blowflies were investigated. Larvae were reared on liver substrates homogeneously spiked with aliquots of endosulfan corresponding to the concentrations found in body tissues of humans and animals involved in endosulfan poisoning. Results demonstrated that the combination of QuEChERS extraction and GC-MS provide an adequate methods to detect both α- and β-endosulfan in blowfly immatures. Furthermore, the presence of α- and β-endosulfan in the food source 1) prevented C. vomitoria immatures reaching the pupal instar and, therefore, the adult instar at high concentrations, 2) did not affect the developmental time of blowflies at low concentrations 3) affected the size of immatures only at high concentrations, resulting in significantly smaller larvae.

The effect of antifreeze (ethylene glycol) on the survival and the life cycle of two species of necrophagous blowflies (Diptera: Calliphoridae)

Entomotoxicology involves the analysis of the presence and the effects of toxicological substances in necrophagous insects. Results obtained by entomotoxicological studies may assist in the investigation of both the causes and the time of death of humans and animals. Ethylene glycol (EG) is easy to purchase, sweet and extremely toxic. It may be consumed accidentally or purposefully, in an attempt to cause death for suicidal or homicidal intent. Several cases report fatalities of humans and animals. The present study is the first to examine the effects of EG on the survival, developmental rate and morphology of two blowfly species, (Diptera: Calliphoridae) typically found on corpses and carcasses: Lucilia sericata (Meigen) and L. cuprina (Wiedemann). Both species were reared on substrates (beef liver) spiked with three different concentrations of EG that could cause death in either a human or cat: 1/2LD₅₀ (T1), LD₅₀ (T2), 2LD₅₀ (T3), in addition to a control treatment (C) with no EG. Results of this research show that: a) both species are unable to survive if reared on a food substrate spiked with the highest concentration of EG (T3), while lower and medium concentrations (T1, T2) affect, but not prevent, the survival and the completion of the life cycle of such species; b) adults of L. sericata eclose only in C and T1, while adults of L. cuprina in both C, T1, T2; however, c) the developmental time of both species reared in T1 and T2 is statistically slower than the control; d) the body length of the immatures of both of the species reared in T1 and T2 is statistically smaller than the control.

Is PMI the Hypothesis or the Null Hypothesis?

Over the past several decades, there have been several strident exchanges regarding whether forensic entomologists estimate the postmortem interval (PMI), minimum PMI, or something else. During that time, there has been a proliferation of terminology reflecting this concern regarding "what we do." This has been a frustrating conversation for some in the community because much of this debate appears to be centered on what assumptions are acknowledged directly and which are embedded within a list of assumptions (or ignored altogether) in the literature and in case reports. An additional component of the conversation centers on a concern that moving away from the use of certain terminology like PMI acknowledges limitations and problems that would make the application of entomology appear less useful in court-a problem for lawyers, but one that should not be problematic for scientists in the forensic entomology community, as uncertainty is part of science that should and can be presented effectively in the courtroom (e.g., population genetic concepts in forensics). Unfortunately, a consequence of the way this conversation is conducted is that even as all involved in the debate acknowledge the concerns of their colleagues, parties continue to talk past one another advocating their preferred terminology. Progress will not be made until the community recognizes that all of the terms under consideration take the form of null hypothesis statements and that thinking about "what we do" as a null hypothesis has useful legal and scientific ramifications that transcend arguments over the usage of preferred terminology.

X-ray metal assessment and ovarian ultrastructure alterations of the beetle, Blaps polycresta (Coleoptera, Tenebrionidae), inhabiting polluted soil

X-ray analysis was applied to estimate the percentages of heavy metals in ovarian tissues of the tenebrionid beetle, Blaps polycresta. Calcium, phosphorus, sulfur, cadmium, copper, and zinc were the most common detected metals in ovaries of insects collected from reference and polluted sites. Only cadmium showed significantly higher percentages in the polluted ovaries compared with the reference ones. Ultrastructure investigation revealed severe alterations in polluted ovaries both in the tropharium and in the vitellarium. Contraction of nuclear membrane of trophocytes was observed; therefore, cavities and spaces appeared in the cytoplasm followed by nuclear pyknosis. In the vitellarium, fragmentation of chromatin materials in nuclei of the follicular cells was detected. The cytoplasm was poor in the rough endoplasmic reticulum and mitochondria. Damage of yolk bodies occurred in addition to break off in the layer of microvilli. Accumulation of electron-dense vesicles and multivesicular bodies were observed in both reference and polluted ovaries. These alterations in ovarian ultrastructure of B. polycresta show the severe impact of cadmium pollution on cell organelles of insects and could be used as an interesting tool for monitoring heavy metals inside the body organs due to soil pollution.

Forensic entomotoxicology revisited-towards professional standardisation of study designs

Forensic entomotoxicology is the use of insects as evidence of whether a toxicant is present in an environment such as a corpse, river or landscape. The earliest overtly forensic study was published in 1977, and since then, at least 63 papers have been published, most of them focused on the detection of toxicants in insects or on effects of toxicants on diverse insect indicator taxa. A comprehensive review of the published literature revealed various inconsistencies between studies that could be addressed by introducing standard protocols for such studies. These protocols could include selecting widespread and common model organisms (such as Lucilia sericata, Calliphora vicina, Chrysomya megacephala and Dermestes maculatus) and model toxicants (e.g. morphine and amitriptyline) to build up comparative databases; developing a standard matrix for use as a feeding substrate; setting guidelines for statistically adequate sample sizes; and deploying more sophisticated analytical methods from the general field of toxicology. Future studies should then be aimed at refining standardised protocols to improve experimental results, and make these results more comparable between studies.

Insect succession on remains of human and animals in Shenzhen, China

Most forensic entomological succession studies have been carried out using pig or rabbit carcasses; however, there have been few studies on the differences between insect succession patterns on human cadavers and on animal carcasses. In order to clarify the differences between decomposition and insect succession patterns of human cadavers and animal carcasses, one 49.5kg human cadaver, two large pig carcasses (45 and 48kg), two small pig carcasses (23 and 25kg) and two rabbit carcasses (both 1.75kg) were placed in the same field conditions in Shenzhen, China for a comparative study on August, 2013. The results indicated that: (1) The duration from fresh to skeletonization is in order of human cadaver>large pig carcasses>small pig carcasses>rabbit carcasses; (2) insect assemblages (including developmental stages) are more complex on larger carcasses, in order of human cadaver=large pig carcasses>small pig carcasses>rabbit carcasses; (3) the developmental rates of the same forensically important fly species on all carcasses are consistent; (4) all identified species of Calliphoridae can complete development of one generation on human cadaver, and both large and small pig carcasses, while on rabbit carcasses, only a subset of the Calliphoridae species can finish development of one generation; (5) beetles can generate offspring on human cadaver, and both large and small pig carcasses, while they do not generate offspring on rabbit carcasses. This study provides useful comparative data for decomposition and insect succession pattern of human cadaver with animal carcasses.

Effects of different storage and measuring methods on larval length values for the blow flies (Diptera: Calliphoridae) Lucilia sericata and Calliphora vicina

In forensic entomology, the methods of sampling, killing, and storing entomological samples can affect larval age estimation, and, hence, the estimation of the minimum post-mortem interval. In the existing manuals, there is a certain amount of heterogeneity regarding methods and the recommendations for best practice in forensic entomology are insufficiently validated. This study evaluated three different length-measurement methods for larval stages and examined the influence of different killing and storing methods on the larval length of two forensically important blow flies, Lucilia sericata and Calliphora vicina. The three different measuring methods were a) a ruler with a 0.1mm scale, b) a geometrical micrometer, and c) a computer-aided stereomicroscope. They were used to measure the length of L₁-L₃C. vicina larvae and detect no significant differences. This supports the view that a simple tool like a geometrical micrometer can produce reliable results in forensic entomology. Newly hatched larvae of L. sericata and C. vicina were killed with hot water (HW) and divided into two equal subsamples. Lengths of all larvae were measured immediately after killing, then every 24h until day 4, and once more after 7days of storage in ≥70%-ethanol. L. sericata larvae only showed significant changes in length in the HW group stored at room temperature. After 4 and 7days of storage, these 24-h- and 72-h-old larvae showed a significant decrease in length compared with those in a fridge at 6°C. This decrease can, however, be considered a negligible natural variation without forensically relevant consequences for larval age estimation of L. sericata samples. For C. vicina, an increase in length was observed over time. This was significant only for younger larvae (24-48h old) stored in 70%-ethanol. This variance in length can lead to a wrong estimation of age; however, only for larvae stored in 70%-ethanol, not for those stored in 96%-ethanol.

NOVELTY STATEMENT

We examined the influence of different killing and storing methods on two forensically important blow flies, Lucilia sericata and Calliphora vicina. For the latter species we additionally were evaluating three different length measurement methods. The results of both experiments suggest that it is possible to kill and store fly larvae directly in (not hot) ≥70%-ethanol. This simplifies the sampling and storing of fly evidence at the crime scene. We also compared the influence of three different measuring methods for estimating the length of L1-L3 C. vicina larvae by using a) a ruler with a 0,1mm scaling, b) a geometrical micrometer and c) a computer-aided stereomicroscope. No significant differences were detected, supporting the view, that a simple tool like a geometrical micrometer can produce reliable results. This study helps to simplify the sampling and evaluation of entomological evidence and to backup or questioning existing guidelines and best practice recommendations.

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.