Forensic Insects Research Articles

Seasonal Abundance of Forensic Insects Encountered on Rabbit Cadavers in Assiut Governorate Egypt

Seasonal Abundance of Forensic Insects Encountered on Rabbit Cadavers in Assiut Governorate Egypt

Forensic entomology as an advanced tool in crime investigation

The use of research on insects and other arthropods in court proceedings is known as forensic entomology. When forensic insects are discovered on a human body or at the crime scenes, their biodiversity, biology, ecology, and behavior can reveal details about the period since death and occasionally even the reason of the death. The forensic insects have been utilized in criminal investigations from decades, they have only recently become a very well-known and separate field in forensic investigations. Knowledge of local insect assemblages and population dynamics is crucial in medico-legal entomology for a successful criminal investigation when monitoring and analyzing insects on a corpse. Forensic entomology comprises three subspecialties, namely urban, stored goods, and medico-legal. The insects that colonize corpses provide valuable insights into the decomposition process. In cases where traditional methods for determining the time since death are limited, Calliphoridae, a family of flies, provides crucial evidence. Two well-established approaches for estimating the post-mortem interval rely on the development of maggots and the succession patterns of insect species. Forensic entomology has gained significant popularity among criminal investigators and forensic entomologists, leading to the emergence of various related fields.

Comparative Study on Forensic Insects encountered on Rabbit Corpses killed with different methods in Upper Egypt

Comparative Study on Forensic Insects encountered on Rabbit Corpses killed with different methods in Upper Egypt

Forensic entomology: A novel approach in crime investigation

Forensic entomology is an application of studies related to insects and other arthropods in legal matters. Depth knowledge and experience of the biodiversity, biology, ecology, and behavior of forensic insects found on a human corpse or at a crime site, can provide information about time since death, location of the crime, and in some cases cause of death. Although forensic insects are used in crime investigation for three to four decades, it aroused recently as a very popular and independent branch of forensic science in crime investigation. While observing and examining insects on a corpse, knowledge of regional insects’ assemblages and their population dynamics play an important role in medico-legal entomology for an efficient criminal investigation. Forensic entomology has three components, named as urban, stored products, and medico-legal. As different groups of insects are attracted to different stages of decay, forensic insects invade the corpse in a typical sequence. The type of insects’ colonization found on corpses provides important information about the decomposition stage. Calliphoridae provides valuable evidences, particularly in determining time since death in criminal matters, where the time since death is prolonged and use of other conventional methods for estimation of time since death is limited. Two well-established ways used for estimation of post mortem interval are based on maggot’s development and succession waves of entomofauna. The latest scientific and technological developments in the field, such as its combined approach with forensic toxicology, forensic palynology, DNA based molecular identification of insect species, and other various methods to estimate post mortem interval, are many emerging fields under this periphery and forensic entomology lately became very popular among criminal investigators and forensic entomologists.

Diversity and dynamics of bacteria at the Chrysomya megacephala pupal stage revealed by third-generation sequencing

Characterization of the microbial community is essential for understanding the symbiotic relationships between microbes and host insects. Chrysomya megacephala is a vital resource, a forensic insect, a pollinator, and a vector for enteric bacteria, protozoa, helminths, and viruses. However, research on its microbial community is incomprehensive, particularly at the pupal stage, which comprises approximately half of the entire larval development stage and is important entomological evidence in forensic medicine. For the first time, this study investigated the bacterial communities of C. megacephala pupae at different ages using third-generation sequencing technology. The results showed that C. megacephala has a diverse and dynamic bacterial community. Cluster analysis at ≥ 97% similarity produced 154 operational taxonomic units (OTUs) that belonged to 10 different phyla and were distributed into 15 classes, 28 orders, 50 families, 88 genera, and 130 species. Overall, the number of bacterial OTUs increased with the development of pupae, and the relative abundance of Wolbachia in the Day5 group was significantly lower than that in the other groups. Within the pupal stage, Proteobacteria, Firmicutes, and Bacteroidetes were the dominant phyla of bacteria. At the genus level, Wolbachia and Ignatzschineria coexisted, a rarely known feature. In addition, we found Erysipelothrix rhusiopathiae, the etiological agent of swine erysipelas, which is rarely identified in insects. This study enriches the understanding of the microbial community of C. megacephala and provides a reference for better utilization and control of C. megacephala.

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

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

Detection of forensic insects invading internal organs of sheep left indoors in the terrestrial area in the autumn season in Aksaray province

Detection of forensic insects invading internal organs of sheep left indoors in the terrestrial area in the autumn season in Aksaray province

A Comparative Study on the Prevalence of Forensic Flies using Chicken Corpse

Forensic entomology is used as evidence of crime incidents especially to a murder case using biological and ecological habits of insects. We wondered how insects can be the key to solving cases by studying insects collected at the scene, so started this study. The decay of the corpse is influenced by the environmental factors, physical conditions or conditions of corpse at the sites, therefore, in order to confirm the hypothesis that types or groups of flies will be different from the sites separately, We compared with the occurrence of flies to different sites according to decay stages of chicken. The chicken corpse was placed in cages made of wire mesh from June 16 to July 20, 2019 at four different sites in Kunsan National University, and a sticky wrap was attached to the cage lid. Sticky traps were collected and replaced daily from 14:00 to 16:00 from June 18 to June 30, and every three days from July 1 to July 20, and the temperature and humidity also were recorded. In addition, a random selection of flies on the sticky trap was carried out for molecular identification of a total of 18 flies. A total of 20 collections were performed, and a total of 1,139 flies were observed in the entire trap. Most of the areas where flies were more collected were a pine forest and a meadow. It was confirmed that the temperature were lower in the pine forest than in other regions, and the humidity in the pine forest was maintained at 70-80%. At the beginning of the trap installation, many flies were collected, and the number of flies collected thereafter decreased. After the rain, the number of flies collected briefly increased. The number of flies was estimated to be related to temperature and humidity, and the Mantel test was used to determine their correlation. As a result, it was confirmed that the number of flies varies with temperature. As a result of molecular identification using COI markers to determine which flies mainly came from, they were identified: Chrysomya pinguis, Anthomyia illocata, Hydrotaea ignava and Hydrotaea leucostoma. We confirmed that the density of flies has been found to be affected by the surrounding environment, the flies, which are known to be the first to fourth group flies that visit the corpse depending on the decay time of the corpse, were coming at the same time, supposing to affected by the decay rate and incision of the corpse. As a result of DNA identification, most of the collected flies were Chrysomya pinguis and Hydrotaea leucostoma was found unrecorded species in South Korea. The results of this study may be useful as basic data for the study of forensic insect flies in the Gunsan.

Dynamic transcriptome profiling exploring cold tolerance in forensically important blow fly, Aldrichina grahami (Diptera: Calliphoridae)

BackgroundAldrichina grahami (Diptera: Calliphoridae) is a forensically important fly, which has been widely applied to practical legal investigations. Unlike other necrophagous flies, A. grahami exhibits cold tolerance which helps to maintain its activity during low-temperature months, when other species are usually not active. Hence, A. grahami is considered an important forensic insect especially in cold seasons. In this study, we aim to explore the molecular mechanisms of cold tolerance of A. grahami through transcriptome.ResultsWe collected eggs and larvae (first-instar, second-instar and third-instar) at three different temperatures (4 °C, 12 °C and 20 °C) and performed RNA-seq analyses. The differentially expressed genes (DEGs) associated with the cold-tolerance were screened out. The Venn analysis of DEGs from egg to third-instar larvae at three different temperatures showed there were 9 common genes. Candidate biological processes and genes were identified which refer to growth, and development of different temperatures, especially the chitin and cuticle metabolic process. The series-clusters showed crucial and unique trends when the temperature changed. Moreover, by comparing the results of growth and developmental transcriptomes from different temperatures, we found that DEGs belonging to the family of larval cuticle proteins (LCP), pupal cuticle protein (CUP), and heat shock proteins (HSP) have certain differences.ConclusionsThis study identified functional genes and showed differences in the expression pattern of diverse temperatures. The DEGs series-clusters with increasing or decreasing trends were analyzed which may play an important role in cold-tolerance. Moreover, the findings in LCP, CUP and HSP showed more possible modulations in a cold environment. This work will provide valuable information for the future investigation of the molecular mechanism of cold tolerance in A. grahami.

Two human cases associated with forensic insects in Riyadh, Saudi Arabia.

In Riyadh, Saudi Arabia, we are reporting two cases of natural death. The two bodies showed different types of habitat, insect colonization and decomposition stage. The first case was about the body of a 65-years-old male, with mummification of the clothed body was found in an outdoor habitat. Different life stages of Dermestes maculatus DeGeer (Coleoptera: Dermestidae were gathered from the cadaver, and due to the advanced degree of decomposition, the PMImin was estimated to be 3 months. The second body belonging to a 40-years-old male, was found in a semi-closed apartment (indoor habitat), and the body was at the end of the bloated decomposition stage. In this case, Musca domestica L. (Diptera: Muscidae) larvae were collected, and the PMImin was estimated to be 4 days. The limited insect activity for the two bodies caused by the advanced decomposition stage in the first case and indoor environment in the second. Average temperatures of (23.3 ± 1.6) °C for the first body and (27.5 ± 1.7) °C2 for the second body. Habitat was the key factor to attract insects to the two cadavers. This study stressed that, for accurate estimates of time since death, knowledge of the impact of different variables on insects found over and around the carrion is essential.

A study of insects on decomposition stage of pig carcasses at Masarang Forest, North Sulawesi, Eastern Indonesia

To investigate the colonization of Insects on the pig (Sus scrofa Linnaeus) carcasses at Masarang forest, present study was carried out in two ways: pig carcasses weighing 35 kg are laid on the ground, and 2 kg of fresh pork pieces are hung at a height of 2.5 m. Decomposition of pig carcasses weighing 35 kg is found in the stage of fresh, bloat, decay, and skeletal. The forensic insects found in carcasses consist of 6 orders, 23 families, and 32 species. The main insects found on pig carcasses are Diptera and Coleopetara. Dominant insects consist of Chrysomya megacephala, Ophyra albuquerquei, and Nicrophorus vespilloides. The relative abundance of insects starts at the stage of fresh, in its peaks at the stage of decay, and decreases at the stage of skeletal. The C. megacephala came earlier on the pig carcasses, and it became dominant insect from the stage of fresh to decay, aw well as it can be a bioindicator for post-mortem intervals. Likewise, N. vespilloides become dominant and a bioindicatorat at the stage of decay. Larvae of N. vespilloides as predators and meat-eating necrophagous cause the stages of decomposition to be shorter. Variations in species and relative abundance of forensic insects at the stage of decomposition are in the stage of decay. The relative abundance of the highest imago of N. vespilloides are found on pork pieces. Staphylinidae, Gauropterus sp. become dominant at the stage of skeletal, and it can be used as an indicator.

A preliminary investigation of the entomofauna composition of forensically important necrophagous insects in Al-Madinah Al-Munawwarah region, Kingdom of Saudi Arabia

ABSTRACT The key role in forensic entomology is the study of entomofauna composition through species identification, succession, colonization, and developmental rate. In this study, rabbit carcasses were used as a model to identify the forensic insect species in Al-Madinah Al-Munawwarah, Saudi Arabia. The appearance and succession of these insects can help in the estimation of the minimum postmortem interval (mPMI) and in many other applications in this region. During the decomposition process, the most important forensic insects observed were from the orders Diptera and Coleoptera. Seven species in five families of Diptera and four families of Coleoptera were identified. The most abundant species in the area that colonized the carcasses were Chrysomya albiceps Widemann (Diptera: Calliphoridae) and Dermestes maculatus De Geer, which can be used for mPMI estimations. This study was the first conducted in Al-Madinah Region to provide a qualitative assessment of forensically important necrophagous species in this region.

First Insights into the Intrapuparial Development of Bactrocera dorsalis (Hendel): Application in Predicting Emergence Time for Tephritid Fly Control.

Intrapuparial development is a special pattern of metamorphosis in cyclorrhaphous flies, in which the pupa forms in an opaque, barrel-like puparium. This has been well studied in forensic insects for age estimations. In this study, the intrapuparial development of a quarantine agricultural pest, Bactrocera dorsalis (Hendel), was studied under a constant temperature of 27 ± 1 °C and 70 ± 5% relative humidity. Results showed that intrapuparial development could be divided into five stages: Larval-pupal apolysis, cryptocephalic pupa, phanerocephalic pupa, pharate adult, and emergent adult. It lays a morphology-based foundation for molecular mechanism studies and enhances the understanding of the physiological basis for changes in intrapuparial development. More importantly, the chronology of intrapuparial development can be used to predict the emergence time of tephritid flies, indicating when to spray insecticides to control these phytophagous agricultural pests. This may be an effective approach to reduce the use of insecticides and slow down the evolution of insecticidal resistance.

Review of Molecular Identification Techniques for Forensically Important Diptera.

The medico-legal section of forensic entomology focuses on the analysis of insects associated with a corpse. Such insects are identified, and their life history characteristics are evaluated to provide information related to the corpse, such as postmortem interval and time of colonization. Forensically important insects are commonly identified using dichotomous keys, which rely on morphological characteristics. Morphological identifications can pose a challenge as local keys are not always available and can be difficult to use, especially when identifying juvenile stages. If a specimen is damaged, certain keys cannot be used for identification. In contrast, molecular identification can be a better instrument to identify forensically important insects, regardless of life stage or specimen completeness. Despite more than 20 yr since the first use of molecular data for the identification of forensic insects, there is little overlap in gene selection or phylogenetic methodology among studies, and this inconsistency reduces efficiency. Several methods such as genetic distance, reciprocal monophyly, or character-based methods have been implemented in forensic identification studies. It can be difficult to compare the results of studies that employ these different methods. Here we present a comprehensive review of the published results for the molecular identification of Diptera of forensic interest, with an emphasis on evaluating variation among studies in gene selection and phylogenetic methodology.

Seasonality of Insect Succession and Dog Carcass Decomposition in Different Habitats

The different collected insect species were distributed on the carcasses according to the decomposition stages or postmortem intervals (PMI). In the winter season, the insect succession showed that carcasses placed outdoor attracted the greatest numbers and highest diversity of insect species. The calliphorid fly; Chrysomya albiceps was first attracted to the bloated and decay stages. In both habitats (outdoor and indoor), the numbers and diversity of insect species on carcasses were decreased during the advanced decay stage and then increased again during the dry stage. In the spring season, Chrysomya albiceps was the first fly attracted to the fresh or bloated stage of dog carcass in both habitats. Moreover, calliphorid flies were disappeared during the advanced decay stage in both habitats. While Coleopteran insects appeared during the decay and advanced decay stages. In the summer season, the forensic insect species showed nearly the same distribution of the different decomposition stages. Also, Chrysomya albiceps was the first fly attracted to the early stages of decomposition. In general, it appeared that the diversity and numbers of forensic insect species, which colonize dog carcass, were increased outdoor and decreased indoor. In the autumn season, carcasses placed outdoor attracted the greater numbers and higher diversity of forensic insects. The calliphorid fly, Chrysomya albiceps,and housefly, Musca domestica were first attracted to the fresh and bloated stages, especially of carcasses placed outdoor. The adult beetles, Dermestes maculatus, Necrobia rufipes and Hister sp.were early seen during bloated, decay and advanced decay stages.

The Abundance of Forensic Insects on Dog and Rabbit Carcasses in Different Habitats and Developmental Stages of Chrysomya albiceps as a Forensic Indicator

The Abundance of Forensic Insects on Dog and Rabbit Carcasses in Different Habitats and Developmental Stages of Chrysomya albiceps as a Forensic Indicator

Forensic insects attracted to human cadavers in a vehicular environment in Riyadh, Saudi Arabia.

Insect fauna attracted to cadavers at the crime scene can be identified and used to estimate the post-mortem interval (PMI). In the current study, insects associated with two human cadavers in a vehicular environment were collected and analysed. The first cadaver was found five days’ post mortem in a garage. The second cadaver was found in a car ten days after his death. The weather conditions were obtained from the nearest weather station located to the scenes of the death. During the study, six adults, 32 larvae and egg batches were collected from case 1 and identified as Chrysomya albiceps Wiedemann (Diptera: Calliphoridae). From the second case, two larvae of Megaselia scalaris Loew (Diptera: Foridae) and seven larvae of Musca domestica L. (Diptera: Muscidae) were identified. mPMI ranged from five to twelve days. This information expands the knowledge on the insect fauna in the vehicular environment, which could be used to assist estimation of the PMI.

Entomofauna Associated with Certain Animal Carcasses as A human Model in Cairo, Egypt

The current study was carried out to investigate the forensic insects associated with two animal carcasses namely; dog (Canis lupus familiaris)and rabbit (Lepus cuniculus) during the summer season. A total of 687 adult insect specimens representing 9 families were collected from dog carcass placed outdoor, while 342 adult insect specimens representing 8 families were collected from dog carcass placed indoor. Diptera, Coleoptera and Hymenoptera comprised 57 %, 36 % and 7 % of insects collected from dog carcasses placed outdoor and 59 %, 37 % and 4 % of insects placed indoor. A total of 274 adult insect specimens representing 8 families were collected from rabbit carcass placed outdoor, while 68 adult insect specimens representing 5 families were collected from rabbit carcass placed indoor. Diptera, Coleoptera and Hymenoptera comprised 70 %, 19 %, 11 % and 46 %, 38 %, 16 % of the insect collected from rabbit placed outdoor and indoor, respectively. The insect succession on dog and rabbit carcasses throughout the decompositional stages showed that the Calliphorid fly, Chrysomya albiceps was the first fly attracted to the early stages of decomposition. In general, it has appeared that the diversity and numbers of forensic insects which colonize dog or rabbit carcasses were increased outdoor and decreased indoor. Moreover, forensic insects were higher in numbers on dog carcasses than on rabbit carcasses.

Comparitive Study on Outdoor and Indoor Forensic Insects encountered on Rabbit Corpses in Upper Egypt

Comparitive Study on Outdoor and Indoor Forensic Insects encountered on Rabbit Corpses in Upper Egypt

Scanning electron microscopic studies on antenna of Hemipyrellia ligurriens (Wiedemann, 1830) (Diptera: Calliphoridae)—A blow fly species of forensic importance

Blow flies (Diptera: Calliphoridae) are one of the foremost organisms amongst forensic insects to colonize corpses shortly after death, thus are of immense importance in the domain of forensic entomology. The blow fly Hemipyrellia ligurriens (Wiedemann, 1830) (Diptera: Calliphoridae) is considered as a forensically important fly species globally and is also known for its medical and veterinary importance. In the present study, we report for the first time scanning electron microscopic studies on the morphology of sensilla of antenna of adult male and female of H. ligurriens is with profound importance in better understanding of the insect morphology from forensic entomological perspective, and also could aid in proper identification of the species from other calliphorid flies. The structural peculiarities observed in the (i) antenna of H. ligurriens with three segments- scape, pedicel and flagellum with dorso-laterally placed arista (ii) densely covered microtrichia and most abundant trichoid sensilla identified on the antenna (iii) observation of only one type of sensilla, chaetic sensilla (ChI) on the scape (iv) two types of chaetic sensilla (ChI and ChII) and styloconic sensilla on the pedicel (v) the flagellum with three types of sensilla- trichoid, basiconic and coeloconic sensilla (vi) Basiconic sensilla with multiporous surfaces with characteristic olfactory function. Moderate sexual dimorphism in the width of the flagellum, the females with wider flagella than the males, bear significance to the fact that they bear more multi-porous sensilla than the males, thus suffice their need to detect oviposition sites. Significant difference was observed in the length and width of coeloconic sensilla between the two sexes, the females showed bigger coeloconic sensilla, suggesting their function in oviposition site detection and successful colonization in corpses.