Forensic Importance Research Articles

Brief Review of Morphological Characters in the Identification of Muscomorpha (Diptera) of Sanitary and Forensic Importance

With more than 125,000 described species, Diptera are considered a megadiverse order. However, immatures display great morphological homogeneity, making few species of Diptera from the Cyclorrhaphan group easy to identify. The main species of medical, sanitary, and forensic importance are found in this group, highlighting the relevance of their description. The uniformity of the group limits sensitive techniques for identifying immatures; therefore, this study reports characters that can be used to identify these insects using scanning electron microscopy. Based on an investigation and analysis of the relevant scientific literature, we suggest combining techniques for accurate morphological identifications of flies.

Forensic Importance of Aquatic Arthropods and Molecular Biomarkers in Criminal Investigations on Floating Cadavers: A Narrative Review

Forensic Importance of Aquatic Arthropods and Molecular Biomarkers in Criminal Investigations on Floating Cadavers: A Narrative Review

Insects on Decomposing Pigs and their Forensic Importance at a University in Nigeria

The use of insects to estimate post-mortem interval (PMI) of cadavers by forensic entomologists, is an innovative science enshrined in the medico-criminal system of the developed world. The science is dependent on the biology of insect species that are found in decomposing cadavers. Thus, insect species that are found on decomposing pigs as model to human cadaver, was studied during the rainy and dry seasons of 2021 in a University forest in Nigeria. The decomposition stages (fresh through skeletonization) of the pig cadavers were monitored, and insects found on them were collected with a sweep net, visually observed, and handpicked. They were identified morphologically using insect identification keys with the aid of a dissecting microscope. The tissues of the pig cadavers decomposed completely in 14 and 10 days, respectively, for dry and rainy seasons. Twenty-seven insect species belonging to the orders; Diptera, Coleoptera, and Hymenoptera were identified. The dipterans consist of the families Calliphoridae, Muscidae, Ulidiidae, and Stratiomyidae. The coleopteran families are the Carabidae, Chrysomelidae, Cleridae, Dermestidae, Histeridae, Scarabaeidae, and Staphylinidae, while Formicidae is the only family for the hymenopteran. The dipteran species were the first group to visit the cadavers during fresh, bloated, and wet decay stages while the coleopterans visited during wet and dry decay stages thus, creating a succession pattern on the cadavers. The insect species that aided the cadaver decomposition at different stages are discussed as forensic indicators, which could be useful as PMI estimators of the study area.

First description of immature stages and notes on the biology of the blow fly, Calliphora lopesi Mello, 1962.

Several species of the worldwide distributed genus Calliphora Robineau-Desvoidy (Insecta, Diptera, Calliphoridae) are medically important vectors and agents of myiasis. Furthermore, these flies are relevant in forensics because they are found in corpses. Information regarding the taxonomy, bionomics and distribution of Calliphora species endemic to South America, including Calliphora lopesi Mello, is scarce. To expand knowledge on C. lopesi, this study presents descriptions of eggs, larvae, puparia and developmental data at 14, 17, 20, 23 and 26 ± 1°C for the first time. Adult flies were collected from the field and kept in the laboratory to obtain samples for morphological and biological studies. Immatures were examined using light and scanning electron microscopy. To assess the growth rate, 10 specimens from each temperature group were randomly removed from the diet and weighed every 24 h from larval hatching until pupation. The minimum developmental threshold, thermal constant and linear development-rate equations were calculated for each stage. Considering weight gain records and survival rates, the optimum temperature for the development of C. lopesi ranges from 23 to 26°C. A key to third-instar larvae of known Neotropical species of Calliphora was also provided to assist in identification. The information provided in this study should be useful in expanding knowledge about Neotropical Calliphoridae species of forensic importance.

A preliminary note on attraction and oviposition preferences of Chrysomya rufifacies (Macquart) (Diptera: Calliphoridae)

Chrysomya rufifacies (Diptera: Calliphoridae) is a blow fly species of forensic importance, documented to have a strong preference for colonisation of substrate already inhabited by heterospecific blow fly larvae, thus exhibiting secondary colonisation behaviour. Larvae exhibit predatory behaviour that may be useful to support development where food substrate is limited or high competition exists, but they may alternately be drawn to pre-colonised substrate to capitalise on the advantages of collective exodigestion by previous/current colonisers. Previous authors have suggested female Ch. rufifacies may use visual orientation to detect substrate currently colonised by heterospecific larvae, rather than chemoreception of volatile organic compounds (VOCs), that signify condition of substrate, which would infer that active colonisation is likely a more important oviposition cue for Ch. rufifacies than substrate condition. This study addressed attraction as well as oviposition, examining whether the condition of substrate (either previously colonised or never colonised) or the presence of heterospecific larvae was more important in the initial choice of food source by female Ch. rufifacies where conspecifics were not present, and whether the condition of substrate and presence of heterospecific larvae affects the number of offspring deposited by a female. Attraction was studied using a Y-olfactometer system, and oviposition using a binary-choice assay, with females responding to pairwise choice between an array of meat conditions (fresh, larval aged or aged) and presence/absence of Lucilia sericata larvae. Females displayed a hierarchy of choice of larval aged substrate > aged substrate > fresh substrate, with the active presence of heterospecific larvae a secondary factor in choice. Females produced higher offspring numbers on meat that was either currently or previously colonised by heterospecific larvae, demonstrating the importance of heterospecific indicators of previous or current colonisation as an oviposition cue. This serves as an important consideration for entomologists working with Ch. rufifacies in any capacity where other blow fly species may be present, and most importantly for forensic entomologists where time of colonisation is utilised to estimate PMI.

Molecular identification of blowfly species (diptera: calliphoridae) and beetles (coleopterans) of forensic importance associated with pig (sus scrofa) carrion in Nigeria

Molecular identification of blowfly species (diptera: calliphoridae) and beetles (coleopterans) of forensic importance associated with pig (sus scrofa) carrion in Nigeria

Forensically Valuable Odonatological Records Documentation in an Era of Electronics: How Aware Are the Dental Fraternity?

Forensic odontology plays a pivotal role in the identification of victims in mass disasters with the help of "Preserved dental records" available to general dental practitioners (GDPs). Comparison of dental data obtained from the deceased person with dental data obtained by the dentist from the person's file is a primary method of identification through dental evidence. We explored the practice of maintaining dental records among GDPs, as well as their knowledge of legal regulations and the application of dental records in forensic odontology. Two hundred fifty dentists participated in an online survey. Questions covered general information on dentists, maintenance of dental records, and knowledge of legal requirements and forensic odontology. Overall, 85.2% of dentists obtain and archive written informed consent, while 73.2% retain records in the form of dental cast. Generally, non-carious dental lesions and developmental dental anomalies were not recorded. About 90.8% of dentists use Fédération Dentaire Internationale (FDI) notation. The survey revealed different practices in the maintenance of dental records, including significant flaws and a lack of awareness of their forensic importance. This obvious need for additional education on the proper maintenance of dental records could be met by including forensic odontology in compulsory undergraduate courses and postgraduate dental education. Establishing national and international standards in dental charting would comply with contemporary trends in health care and the requirements of forensic expertise.

An illustrated identification key to early instar larvae of forensically important Muscidae (Diptera) of the western Palaearctic region

There is a significant gap in the availability of comprehensive identification keys for the early larval stages of forensically important fly species. While well-documented identification keys exist for the third instar larvae, particularly for the Calliphoridae, Muscidae and Sarcophagidae families, there is a notable scarcity of keys for the first, except Calliphoridae, and the second instar larvae, with no such resources available for muscid species. The second instar larvae suffer the most from the lack of morphological descriptions and available identification keys. The Muscidae is one of the most frequently reported dipteran families of forensic importance colonising animal cadavers and human corpses. Nevertheless, descriptions of the morphology of their early instars remain scarce and limited to only a few species, thus their larval identification is challenging or impossible. Considering the numerous challenges associated with studying small-sized entomological material, we tested whether it is feasible to identify muscid flies to the species or at least genus level based predominantly on the details of the cephaloskeleton. To overcome the obstacle of observing details of small sclerites, especially their shapes and interconnections, we effectively employed confocal laser scanning microscopy (CLSM) as a supplementary method for light microscopy (LM). This study provides an identification key for first and second instar larvae of forensically important muscid species from the western Palaearctic (Europe, North Africa, Middle East). The proposed key primarily utilises details of the cephaloskeleton with only addition of external morphology.

Intrapuparial development of Sarcophaga (Liopygia) ruficornis (Diptera: Sarcophagidae), a species of medical-veterinary and forensic importance, under laboratory conditions.

Sarcophaga (=Parasarcophaga) (Liopygia) ruficornis (Fabricius, 1794) is a species of medical-veterinary and forensic importance, as its immatures cause myiasis in humans and animals and colonize carcasses and cadavers. Therefore, investigations into the biology and morphology of this species, with a particular focus on pupae that constitute ≥50% of the developmental period for the immatures, are pertinent. Although there are biological and morphological studies of pupae, the intrapuparial development at different temperatures has not yet been analysed. Therefore, the present study aimed to describe how temperature (22, 27 and 32 ± 1°C) affects the development and morphology of S. (L.) ruficornis pupae at 60 ± 10% relative humidity and a 12-h photoperiod. Ten pupae were collected, euthanized and fixed every 4 h from pupariation until 24 h and every 8 h until the emergence of the first adult. Emergence occurred at 440, 272 and 232 h at 22, 27 and 32°C, with 590, 380 and 330 pupae, respectively. The highest mortality occurred at 32°C. Eight periods were defined, and sex was determined in pharate adult stage; in addition, 40 key morphological characteristics to estimate pupal age were presented. These findings can serve as a basis for studies on the biology and morphology of the pupa of S. (L.) ruficornis, particularly in bionomics, control and forensics, helping researchers and experts.

Method of laboratory rearing of flies Hemilucilia segmentaria (Fabricius, 1805) and Hemilucilia semidiaphana (Rondani, 1850) for therapeutic purposes

The blowflies Hemilucilia segmentaria and Hemilucilia semidiaphana are species of forensic importance and, as a scavengers, they have potential in Larval Therapy (LT). LT consists of sterile fly larvae to treat lesions with necrotic tissue. It is an descriptive exploratory laboratory and field study, which aims to describe the methods of rearing flies under laboratory conditions for therapeutic purposes. The staging period from egg to adult was 10.1 days for H. semidiaphana and 12.2 days for H. segmentaria. Considering that they are neotropical species, they need a room temperature ranging from 27 to 29 Cº, humidity of 80± 10% and a light/dark cycle of 12 hours were adopted. The larvae were feeded with ground beef in room temperature and the adult diet varied according to the purpose of rearing. In the egg sterilization process for LT, the most accessible solution, which achieved the highest egg hatching rate, was 1% sodium hypochlorite. The aim of study is to use the larvae to treat injuries. The breeding methods can be use any scientific purposes that require evaluating these species.

Forensic investigation of carcass decomposition and dipteran fly composition over the summer and winter: a comparative analysis of indoor versus outdoor at a multi-story building.

This study aimed to explore the rate of decomposition of rabbit carcasses and the succession pattern of the associated dipteran flies outdoor, indoor, and on the roof of a 4-story building during the summer and winter. A total of 6,069 flies were recorded, with 30.91% reported as 2 waves outdoor and on the roof in the summer and 69.09% as 4 waves outdoor in the winter. The roof showed the most flies in the summer but the least in the winter, whereas the outdoor showed the most in the winter but the least in the summer. The ground and first floors showed the most indoor flies, while the second and third floors showed the least in both seasons. Indoor carcasses decomposed slower than those outdoor, and those on the second and third floors decomposed slower than those on the ground and first floors. Ten fly species from 8 families were identified in the winter, compared to 6 from 5 families in the summer. The most abundant species was Musca domestica Linnaeus (Muscidae) on the roof in the summer, while it was Chrysomya albiceps (Wiedemannn) (Calliphoridae) outdoor in the winter. The rare species (singletons) were Musca sp. (Muscidae) and Megaselia scalaris (Loew) (Phoridae) on the first floor in both seasons, Scaptomyza pallida (Zetterstedt) (Drosophilidae) on the ground floor in the summer, and Atherigona orientalis Schiner (Muscidae) outdoor in the winter. These data highlight the variance in carcass decomposition and fly composition across outdoor, indoor, and the roof of human dwellings, which could be of forensic importance.

Detection of ABO Blood Groups From Dentin and Pulp by Using the Absorption-Elution Technique: A Forensic Cross-Sectional Study Among the Population of the Al Jouf Province, Saudi Arabia.

Background and objective Human teeth have a significant forensic importance. As they are the hardest of all human tissues, they are not just chemically stable but also their characteristics are maintained for a long time after death even in the most harsh environmental conditions. Despite the advances made in DNA analysis, fingerprinting, etc., ABO blood grouping still plays a significant role in the forensic practice in the field of personal identification, paternity disputes, and several other scenarios including the identification of mass disaster victims. The term blood groups refers to inherited antigens on the surface of red blood cells (RBCs) detected by specific antibodies. Since tooth pulp contains numerous blood vessels, blood group antigens are most certainly bound to be present in tooth pulp. Various studies have shown that blood group antigens in the pulp and dentin are preserved as long as up to two years after the demise of an individual. Absorption-elution technique has been proven to be the most sensitive, reliable, and consistent method to determine the ABO blood group from both the pulp and dentine.This study aimed toascertain the ABO blood group from both the hard (dentin) as well as the soft tissue (pulp) of the tooth by using the absorption-elution (AE) technique and also to determine if there are any variations in identifying the blood groups from the teeth based on age and gender. Material and methods After obtaining due consent, we included patients of both genders aged between 16-60 years visiting the outpatient department (OPD) clinics at the College of Dentistry for periodontal or orthodontic extractions.One patient's blood type was determined by using the slide agglutination technique before any capillary blood extraction was performed; this patient served as a control. For this investigation, we used the pulp and powdered dentin samples taken from the dental extractions to test for the presence of ABO and Rhesus (Rh) factor antigens by using the AE method. The study samples were compared with the control for blood group determination. Statistical analysis was carried out using the chi-square test with Monte Carlo (MC) simulation to check for any correlation of blood grouping with age and gender. Results The dentin and pulp were shown to have positive blood group antigens for the ABO and Rh factors.While neither pulp nor dentin performed significantly differently in identifying the blood group antigens, pulp showed marginally higher accuracy.There was no discernibledifference regarding gender or age in the dentin or pulp of any of the 45 samples studied. Conclusions For determining an individual's blood type and Rh factor, both the hard (dentin) and soft (pulp) tissues of a tooth are valid sources. This is particularly helpful in forensic medicine cases where teeth are the onlyremains that can be viably used to find out a person's identity.

Geometry of posterior larval spiracles to identify medically and forensically important calliphorids in Thailand

Fly identification is the primary step of analysis in forensic entomology. Although morphology and molecular techniques are considered satisfactory methods, some constraints may arise from a financial or even human point of view. Over the past decade, the geometric morphometric approach has been increasingly advocated for the classification and identification of arthropods. This study explored the method for species identification of 800 third-instar larvae of eight blow fly species of medical and forensic importance: Chrysomya chani Kurahashi, Chrysomya megacephala (Fabricius), Chrysomya (Ceylonomyia) nigripes Aubertin, Chrysomya pinguis (Walker), Chrysomya (Achoetandrus) rufifacies (Macquart), Hemipyrellia ligurriens (Wiedemann), Lucilia cuprina (Wiedemann), and Lucilia porphyrina (Walker). Based on the posterior spiracles geometry, the cross-validation revealed a relatively high percentage of correct classification in most species, ranking from 86% to 100%. The results of this study confirmed that the geometric morphometric (GM) analysis of posterior spiracles might be utilized as a larva identification tool. Therefore, this GM method represents one way of overcoming difficulties with the identification of blow fly larvae and can support further studies of these flies.

A Review on High Performance Thin Layer Chromatography

A common excellent replacement for GC and HPLC is High-Performance Thin Layer Chromatography (HPTLC), an improved and automated technique of thin-layer chromatography (TLC) that provides better separation performance and detection limits. Applications of HPTLC include the study of biological materials and phytochemicals, the measurement of herbal medications and active components, formulation fingerprinting, and the identification of adulterants in formulations. Using HPTLC, chemicals of forensic importance can be located. It is more sensitive and feasible to run many samples in a little period of time by using a small volume of solvent. It is one of the more intricate instrumental procedures, utilizing every feature available in thin-layer chromatography.

Development and Optimization of a SPME-GC-FID Method for Ethanol Detection

A solid-phase microextraction (SPME) injection gas chromatography was validated with the flame ionization detection method (GC-FID) using a capillary column to detect ethanol. The method was used to determine ethanol in fluids with biomedical, clinical, and forensic importance, including water, phosphate-buffered saline (PBS), and artificial sweat. The strategy produced good peak resolution and showed a linear correlation between the concentration and peak areas for ethanol in all matrices. The inter- and intra-day precisions of the method were below 15.5% and 6.5%, respectively, varying according to the matrix. The method achieved detection limits below 1.3 mg/L, varying according to the matrix. Lower limits were obtained for the aqueous solution (0.22 mg/L), followed by the PBS solution (0.96 mg/L), and finally, the sweat solution (1.29 mg/L). This method is easy to perform and suitable for use in routine clinical biochemistry and forensic laboratories, allowing ethanol detection at lower concentrations using lower temperature and time of extraction, when compared with other studies.

Initial blow fly (Diptera: Calliphoridae) colonization of cats (Felis catus) in Indiana.

Many disciplines are utilized within the field of veterinary forensic sciences, including forensic entomology. Understanding the initial colonization period by flies of forensic importance can contribute to estimating the minimum postmortem interval. There is limited data regarding the time of colonization of animals with fur, and the interpretation of this data is difficult due to the variation in animal models used. The purpose of this study was to examine the initial insect colonization of cats (Felis catus), with light and dark fur. Twelve domestic short-haired cats were placed in cages 15.2 m apart in a grassy field in West Lafayette, IN, United States. Weather data (temperature, precipitation, sun/cloud exposure, humidity), insect activity, time to oviposition, and decomposition changes were documented. Eggs from initial oviposition events were collected and reared to identify the primary colonizing species. Although the time of first oviposition event was not different between the treatments, fur color did affect fly colonization, and cats with dark fur had more oviposition events than cats with light fur (t = 2.639, df = 4, P = 0.029). Three species of Lucilia (Diptera: Calliphoridae) colonized the cats on the initial day of placement. Further studies in cats should include the decompositional studies to understand the unique characteristics that occur during each stage of decomposition, which could aid in developing a scoring system for animals with fur. Additional studies could include analyzing how fur length would affect colonization.

Key for the identification of third instar larvae of African blowflies (Diptera: Calliphoridae) of forensic importance in death investigations

Blowfly larvae are the insects primarily responsible for the active stage of decomposition of exposed vertebrate remains and are the most frequently collected entomological evidence during forensic investigations of death. The necrophagous calliphorids in continental Africa that consistently develop on large vertebrate carrion include 11 species belonging to four genera: Calliphora, Chrysomya, Hemipyrellia and Lucilia. Most of these species are widespread in Africa and frequently reported on large animal carcasses and carrion and human corpses. A few keys have been compiled for identification of their third instar larvae, but none of them covers the complete set of taxa. Therefore, we provide a new comprehensive key with original illustrations of all taxonomically significant characters. The key is based on characters that should be easily observable even in poorly equipped local laboratories and is a reliable taxonomic tool for material collected in either urban or rural areas where synanthropic species predominate. However, it should be used with some caution in areas with relatively pristine natural habitats, where additional carrion-breeding species may occur. The publication of the key will significantly facilitate both medical and forensic entomological research and practice in Africa.

Characterization of intrapuparial development of Musca domestica (Diptera: Muscidae), under different temperatures in laboratory conditions.

Musca domestica (Linnaeus, 1758) (Diptera: Muscidae), popularly known as "housefly", is a highly synanthropic species, with economic, medical-sanitary, veterinary, and forensic importance. It is able to cause damage to health, transmit pathogenic agents, cause infection in domestic animals, and, in its immature stage, cause secondary myiasis. The scavenging habit of its immature stages makes these flies pioneers in colonizing both human and animal carcasses, from the initial stages of corpse decomposition to the final stages. Intrapuparial development studies of all stages of the biological cycle of these insects help estimate pupal age, being useful to forensic entomology to aid in determining the minimum postmortem interval (minPMI). This study describes, morphologically, the external structures of the pupae, under temperatures of 23, 27, and 30 ± 1 °C aiming to identify the characteristics that define their developmental stages and estimation of the pupae age of M. domestica. The whole experiment was carried out under laboratory conditions, with relative humidity 60 ± 10% and 12 hours of photoperiod. The process of pupariation and pupation including pre-pupae phases were observed; larvae pupae apolysis; early cryptocephalic pupae; late cryptocephalic pupae; phanerocephalic pupae; pharate adult, discriminated by eye color (transparent eyes, pink eyes, and red eyes); and the emergency of adults, which occurred in the intervals of 162-180; 138-144, and 96-102 hr, respectively, being described throughout the metamorphosis of the external morphological characteristics of the pupal stage of M. domestica.

Effects of antibiotics ceftriaxone and levofloxacin on the growth of Lucilia sericata (Diptera: Calliphoridae).

Lucilia sericata is one of the most studied species in forensic entomology due to its widespread distribution, forensic importance as well as medical use. The growth and development stage of maggots is often used to determine the post-mortem interval in forensic cases. L. sericata can cause myiasis in humans who are not able to maintain personal hygiene due to age or medical condition and can therefore be used to determine the time period of neglect. The influence of the temperature on the maggot development has been examined in various studies. Different examinations on the effects of toxic substances on the maggot development and survival have been conducted in order to test the influence and resulting deviations. In this study, the effects of different therapeutical doses of the antibiotics ceftriaxone and levofloxacin were examined on L. sericata in order to determine and compare deviations in maggot development and survival. The used antibiotics did not significantly influence the maggot weight and length. A significant delay in the time of pupation has been determined in the treatments with high concentrations of levofloxacin. The mortality was significantly increased in all treatments with antibiotics compared to the control, whereby the survivability of all treatments remained over 80%. Because of the high doses needed to produce an effect, we concluded that an overestimation of the post-mortem interval is unlikely but higher antibiotic concentrations or possible interactions with other medications could increase the maggot development time.

Machine learning analysis of wing venation patterns accurately identifies Sarcophagidae, Calliphoridae and Muscidae fly species.

In medical, veterinary and forensic entomology, the ease and affordability of image data acquisition have resulted in whole-image analysis becoming an invaluable approach for species identification. Krawtchouk moment invariants are a classical mathematical transformation that can extract local features from an image, thus allowing subtle species-specific biological variations to be accentuated for subsequent analyses. We extracted Krawtchouk moment invariant features from binarised wing images of 759 male fly specimens from the Calliphoridae, Sarcophagidae and Muscidae families (13 species and a species variant). Subsequently, we trained the Generalized, Unbiased, Interaction Detection and Estimation random forests classifier using linear discriminants derived from these features and inferred the species identity of specimens from the test samples. Fivefold cross-validation results show a 98.56 ± 0.38% (standard error) mean identification accuracy at the family level and a 91.04 ± 1.33% mean identification accuracy at the species level. The mean F1-score of 0.89 ± 0.02 reflects good balance of precision and recall properties of the model. The present study consolidates findings from previous small pilot studies of the usefulness of wing venation patterns for inferring species identities. Thus, the stage is set for the development of a mature data analytic ecosystem for routine computer image-based identification of fly species that are of medical, veterinary and forensic importance.