Entomological Evidence Research Articles

Developmental rate, size, and sexual dimorphism of Megaselia scalaris (Loew) (Diptera: Phoridae): its possible implications in forensic entomology.

Cosmopolitan scuttle fly, Megaselia scalaris (Loew) (Diptera: Phoridae) is one of the commonest forensic species recorded colonizing human corpse indoors and in concealed environment. The occurrence of this species in such environments provides a higher evidential value to assist estimation of postmortem interval (PMI) compared to other forensically important dipterans. However, developmental and size data of M. scalaris are still lacking and they are derived from a limited range of thermal values. The objective of this study is to develop the growth model of M. scalaris by emphasizing the size range of larvae and puparia at different constant temperatures. This species was reared in six replicates at eight varying constant temperatures ranging from 23 to 36°C and cow's liver was provided as food source. Larvae and puparia were sampled at set time intervals and measured by their length and weight. Because interpretation of forensic entomological evidence is subject to application of different techniques, development of M. scalaris is expressed herein by using developmental table, length/morphological stage diagrams and linear/nonlinear estimation methods. From the findings, it is very important to highlight that sexual dimorphism of M. scalaris during post feeding larva and pupa stage could be observed based on size and developmental periods. Mean length and weight ratios of male to female puparia are approximately 0.8 and 0.3-0.5, respectively, indicating sexual dimorphism of this species. Developmental period in female are 4.0-11.4h (post feeding larval stage), 3.7-24.0h (pupal stage), and 3.0-20.1h (total developmental period) longer in male. Due to this dimorphism, PMI estimation using M. scalaris post feeding larva or puparium specimens must be carried out carefully by to avoid inaccuracy and misinterpretation.

The Flesh Fly Sarcophaga (Liopygia) crassipalpis Macquart 1839 as an Invader of a Corpse in Calabria (Southern Italy)

The first aim of forensic entomology is to help investigators estimate the time of death. Its application has become widespread in many countries because the entomological evidence on corpses (especially Diptera and Coleoptera) can be used to estimate the minimum Post Mortem Interval (mPMI) at both indoor and outdoor crime scenes.

Can soil testate amoebae be used for estimating the time since death? A field experiment in a deciduous forest

Estimation of the post-mortem interval (PMI, the time interval between death and recovery of a body) can be crucial in solving criminal cases. Today minimum PMI calculations rely mainly on medical and entomological evidence. However, beyond 4–6 weeks even entomological methods become less accurate. Thus additional tools are needed. Cadaveric fluids released by decomposing cadavers modify the soil environment and thus impact soil organisms, which may thus be used to estimate the PMI. Although the response of bacteria or fungi to the presence of a corpse has been studied, to the best of our knowledge nothing is known about other soil organisms. Testate amoebae, a group of shelled protozoa, are sensitive bioindicators of soil physico-chemical and micro-climatic conditions and are therefore good potential PMI indicators. We investigated the response of testate amoebae to three decomposing pig cadavers, and compared the pattern to two controls each, bare soils and fake cadavers, in a beach-oak forest near Neuchâtel, Switzerland. Forest litter samples collected in the three treatments over 10 months were analysed by microscopy. The pig treatment significantly impacted the testate amoeba community: after 22 and 33 days no living amoeba remained underneath the pig cadavers. Communities subsequently recovered but 10 months after the beginning of the experiment recovery was not complete. The fake cadavers also influenced the testate amoeba communities by altering the soil microclimate during a dry hot period, but less than the cadavers. These results confirm the sensitivity of soil testate amoebae to micro-climatic conditions and show that they respond fast to the presence of cadavers – and that this effect although decreasing over time lasts for months, possibly several years. This study therefore confirms that soil protozoa could potentially be useful as forensic indicators, especially in cases with a longer PMI.

Entomological evidence of misdemeanour

The face of publishing is indisputably changing. As a print-on-demand publication, Insect Evidence is interesting for reasons besides its content. The Internet has freed us of many constraints when it comes to publishing - a situation that is exemplified by the popular fanfiction and academic open-access movements. Fanfic has an effective quality-assurance mechanism, because poor writing receives no encouragement from its reading community, while academic publishing has a two-stage system in which peer reviewers and editors perform an initial gatekeeping role, and the citation system is a secondary mechanism that functions more like that of fanfic. The print-on-demand publishing service industry allows authors to be their own publishers, thus bringing the fanfic model to academic publication.

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The area of forensic entomology has developed to become an increasingly important aspect of forensic science. Insect larvae and adult insects found on human corpses can provide crucial information for the post-mortem interval (PMI) estimation. In July 2010, a decomposing female corpse was found in Xiangjiang River of Changsha section. The main larvae found on the corpse were identified to be Boettcherisca peregrina (Robineau-Desvoidy) by morphologic observation and were then confirmed by mitochondrial DNA sequence. Based on the experimentally obtained entomological evidence, PMI of the female was concluded between 90 and 120 hours. However, eyewitness reports finally confirmed that the elapsed time since death were 128 hours. This case indicates that PMI estimation in terms of the period of insect activity (PIA) is very complicated and concern many factors such as insect species characteristics, weather and seasonality, geographic region. The interaction between forensic entomologists and pathologists in death cases where insects are associated with remains should be encouraged. Key W ords: forensic science, forensic entomology, post-mortem interval, Boettcherisca peregrina, drowning, mitochondrial DNA.

Insects, activity areas and turf buildings' interiors: An ethno-archaeoentomological case study from 19th to early 20th-century Þverá, northeast Iceland

This paper presents the results of an investigation of insect remains preserved in the floors of 19th- and early 20th-century turf buildings. Its aim is to test the potential and limitations of archaeoentomology as a basis for the reconstruction of indoor environments and activities on archaeological sites. The study focuses on the site of Þverá, in northeast Iceland, where previous ethnoarchaeological and geoarchaeological work enabled a detailed understanding of floor formation processes and the cultural practices that took place inside the buildings. Descriptive and multivariate statistics were employed to investigate the formation processes of archaeoentomological assemblages in floors and the extent to which insect faunas can be indicative of functional areas or of the presence of particular materials. The results identify subtle variations between the synanthropic communities and ectoparasites recovered from human living quarters, storage areas and animal stalls, but suggest that it would be difficult to identify a room's function solely on the basis of entomological evidence. Outdoor insects are likely to have become incorporated into floor layers as a result of their transport with hay, turf, peat and water, but as these can be collected from similar environments, it would be difficult to distinguish the entomological signatures for these resources. The insect assemblages from Þverá can be compared confidently with insect faunas preserved in archaeological floor layers from turf buildings and highlight the dangers of uncritical interpretation of entomological data.

Bayesian Networks for Evaluation of Evidence from Forensic Entomology

In the aftermath of a CBRN incident, there is an urgent need to reconstruct events in order to bring the perpetrators to court and to take preventive actions for the future. The challenge is to discriminate, based on available information, between alternative scenarios. Forensic interpretation is used to evaluate to what extent results from the forensic investigation favor the prosecutors' or the defendants' arguments, using the framework of Bayesian hypothesis testing. Recently, several new scientific disciplines have been used in a forensic context. In the AniBioThreat project, the framework was applied to veterinary forensic pathology, tracing of pathogenic microorganisms, and forensic entomology. Forensic entomology is an important tool for estimating the postmortem interval in, for example, homicide investigations as a complement to more traditional methods. In this article we demonstrate the applicability of the Bayesian framework for evaluating entomological evidence in a forensic investigation through the analysis of a hypothetical scenario involving suspect movement of carcasses from a clandestine laboratory. Probabilities of different findings under the alternative hypotheses were estimated using a combination of statistical analysis of data, expert knowledge, and simulation, and entomological findings are used to update the beliefs about the prosecutors' and defendants' hypotheses and to calculate the value of evidence. The Bayesian framework proved useful for evaluating complex hypotheses using findings from several insect species, accounting for uncertainty about development rate, temperature, and precolonization. The applicability of the forensic statistic approach to evaluating forensic results from a CBRN incident is discussed.

Estimativa do intervalo pós-morte em um canino (Canis lupus familiaris Linnaeus 1758) pela entomologia forense em Cabedelo-PB, Brasil: relato de caso

O intervalo pós-morte (IPM) é um instrumento importante de diagnóstico relacionado à prática forense. O uso de insetos tem sido relatado como um modo eficiente para estimá-lo, quando o cadáver encontra-se em estágio avançado de decomposição. Objetivou-se com este trabalho estimar o IPM com base em evidências entomológicas em um canino. Foram coletadas larvas de moscas no cadáver e encaminhadas ao laboratório de entomologia, onde foram criadas e eclodiram adultos da espécie Chrysomya albiceps (Wiedemann, 1819). Somando-se os dados abióticos de temperatura e umidade relativa do local de coleta e do local de criação, estimou-se um IPM mínimo de 3,34 dias do momento da postura dos ovos pelas moscas até a coleta das larvas. Com base nos resultados obtidos, conclui-se que a entomologia forense, como ferramenta para estimativa do IPM, mostrou-se eficaz e determinante na elucidação do caso em questão.

Identification of Forensically Important Sarcophagidae (Diptera) Based on Partial Mitochondrial Cytochrome Oxidase I and II Genes

Entomological evidence is of great importance in forensic cases for postmortem interval calculation. The use of Sarcophagidae (Diptera) for postmortem interval estimation is limited because morphological determination is often hampered because of similar characteristics in the larval, pupal, and even adult stage. To make the species identification more accurate and reliable, DNA-based identification is considered. In this study, we assessed the use of partial mitochondrial cytochrome oxidase I and II genes for discrimination of forensically important Sarcophagidae from Egypt and China [Sarcophaga argyrostoma (Robineau-Desvoidy), Sarcophaga dux (Thomson), Sarcophaga albiceps (Meigen), and Wohlfahrtia nuba (Wiedemann)]. This region was amplified using polymerase chain reaction followed by direct sequencing of the amplification products and using restriction enzymes HinfI and MfeI. Nucleotide sequence divergences were calculated using the Kimura 2-parameter distance model, and a neighbor-joining phylogenetic tree was generated. All examined specimens were assigned to the correct species. Combinations of the restriction enzymes HinfI and MfeI provide different restriction fragment length polymorphism profiles even among 3 sympatric species that belong to the Sarcophaga genus. Therefore, this study demonstrates that the studied partial mitochondrial cytochrome oxidase I and II genes were found to be instrumental for the molecular identification of these forensically important flesh fly species.

Human remains found in two wells: a forensic entomology perspective

When estimating the time since death or manner of death, the identification and the pathological evaluations of a body are generally impeded by post mortem changes. Research and case studies help experts to achieve a more accurate diagnosis, but at present there is scant literature covering topics concerning forensic science and decompositional processes in aquatic environments. The two case studies presented each involve a decomposed body found in a unique aquatic environment; namely wells containing ground water. In Case 1 an entomologist attended the scene and in Case 2 an entomologist was only involved after 20 months when it was decided that the insect evidence collected at the second autopsy may be useful in determining a time frame. The first case highlights the problems associated with body retrieval from aquatic environments as the body was removed it dismembered. Fortunately, the well was able to be drained, so much of the insect evidence was retrieved. In the second case the body was found dismembered but the entomological evidence was overlooked and lost. During the second autopsy insects were found, collected, and sent to an entomologist to help clarify the post mortem interval.

Entomological evidence: Lessons to be learnt from a cold case review

Insects are known to be useful in estimating time since death, but this is only possible if samples are collected and preserved correctly according to best practices. This report describes a case where an 18-year old female was found dead and during the first medico-legal investigation which determined it was a homicide, entomological samples were collected but not considered. The case was then closed with no suspect. However, 9 years after the first investigation the courts decided that the case needed to be re-examined. In doing so the new review team decided that although the remaining entomological evidence was poorly preserved some extra information may be gained from its analyses. On inspection of the remaining samples of larvae no normal morphological analyses could be conducted. Molecular analyses were combined with an unorthodox morphological analysis to provide an estimate of the post-mortem interval based on insect evidence, indicating the value of multidisciplinary approaches to both cold and contemporary cases.

Examination of forensic entomology evidence using computed tomography scanning: case studies and refinement of techniques for estimating maggot mass volumes in bodies

A new technique has recently been developed for estimating the volume of maggot masses on deceased persons using post-mortem CT scans. This allows volume to be measured non-invasively and factored into maggot mass temperature calculations for both casework and research. Examination of admission scans also allows exploration of entomological evidence in anatomical areas not usually exposed by autopsy (e.g. nasal cavities and facial sinuses), and before autopsy disrupts the maggot distribution on a body. This paper expands on work already completed by providing the x-ray attenuation coefficient by way of Hounsfield unit (HU) values for various maggot species, maggot masses and human tissue adjacent to masses. Specifically, this study looked at the HU values for four forensically important blowfly larvae: Lucilia cuprina, L. sericata, Calliphora stygia and C. vicina. The Calliphora species had significantly lower HU values than the Lucilia species. This might be explained by histological analysis, which revealed a non-significant trend, suggesting that Calliphora maggots have a higher fat content than the Lucilia maggots. It is apparent that the variation in the x-ray attenuation coefficient usually precludes its use as a tool for delineating the maggot mass from human tissue and that morphology is the dominant method for delineating a mass. This paper also includes three case studies, which reveal different applications for interpreting entomological evidence using post-mortem CT scans.

DEET (N,N‐Diethyl‐meta‐toluamide) Induced Delay of Blowfly Landing and Oviposition Rates on Treated Pig Carrion (Sus scrofaL.)

The question of whether the insect repellent N,N-Diethyl-meta-toluamide (DEET) affected fly attraction, oviposition, and larval development was investigated; in part, to determine whether the common habit of wearing DEET as a repellent could affect the rate of human decomposition. Experiments using pig surrogates of human decedents were carried out in a rural environment. Dead piglets were sprayed with DEET, and fly behavior, colonization levels, and maggot development were compared with those in nonsprayed controls. Piglets treated with DEET experienced significant delays in fly visitation and oviposition and delayed appearance of each larval instar, as well as reduced total larval numbers (p < 0.01 for all variables), with subsequently reduced decomposition (p < 0.05). Such changes in fly behavior and larval population development would significantly impact the estimation of the period following the death from entomological evidence in decedents wearing DEET at the time of their death.

The Forensic Examination of a Desiccated Body from the Jafr Region, Jordan

Contrary to the strong belief among medical examiners and pathologists in Jordan that all mummified human remains are archaeological, and thus, do not necessitate forensic examination, this Jafr mummy is recent as evidenced by radiocarbon dating. The visual and radiographic examinations showed multiple skull and chest fractures as well as lacerations and cut wounds in various parts of the body. These types of trauma were likely caused by blunt forces applied at multiple sites of the body, typical of those produced in traffic accidents. The entomological evidence suggests a delayed inhumation of at least two days after death.

When Entomological Evidence Crawls Away: Phormia regina en masse Larval Dispersal

In criminal and civil legal investigations the forensic entomologist usually assists in providing an estimate of the postmortem interval, which closely couples with the time or period of insect activity. A minimum period of insect activity is often interpreted and estimated by dipteran larval developmental age of the oldest specimens collected at a crime scene and/or autopsy. In entomological evidence protocols investigators are recommended to search a 2-10 m perimeter area for the oldest larvae that may have begun to disperse away from the body for burial and pupation. In this study, we described a case of a large aggregate (> 90% larvae) en masse postfeeding dispersal of blow fly larvae away from replicate swine carcasses serving as models of human decomposition. Larval dispersal was evaluated for a spring and a summer trial, with en masse characteristics only occurring during the latter. This en masse dispersal occurred in five out of six replicate carcasses and masses moved from 2 to 26 m away. These data and observations suggest the importance of performing searches > 10 m from human remains for entomological evidence at crime scenes. By missing the oldest larvae at a crime scene, interpretation of entomological evidence can be compromised and erroneous. Based on these data and observations we recommend the crime scene investigators and researchers consider increasing the search radius around crime scene remains to increase the likelihood that the oldest larvae have been collected for analysis.

Entomological and Acarological Evidence of Bloodstain Patterns in Forensic Investigation

Entomological and Acarological Evidence of Bloodstain Patterns in Forensic Investigation

돼지사체의 노출 정도에 따른 곤충상과 사체의 부패 패턴에 대한 연구

본 연구는 유기된 돼지사체의 노출 정도에 따른 곤충상의 변화와 부패 패턴을 이용해서 사체의 사후경과시간(Post Mortem Interval, PMI)을 추정하기 위한 기초자료를 얻기 위해 수행되었다. 부산 낙동강 주변의 초지에서 완전노출사체, 감은사체, 덮은사체 및 그늘진사체 각각 1구씩을 2010년 8월에 설치하여 총 7목 15과 20종의 곤충들이 관찰되었고 가장 먼저 접근한 곤충은 검정뺨금파리였다. 검정뺨금파리는 모든 사체에서 전 기간에 걸쳐 출현했으며, 꼭지파리과의 1 종, 왕반날개 및 딱정벌레과의 1종은 부패(III)~백골화(V)단계에 출현하여, 위 4종은 사체의 부패단계를 시사하는 지표곤충으로 유용하다고 생각되었다. 한편, 부패속도는 완전노출사체(7일) > 덮은사체(10일) > 그늘진사체(13일) > 감은사체(15일)의 순으로 빨랐는데, 이는 사체의 노출 정도에 따른 곤충의 접근성 및 큰 비에 의한 사체손실의 정도와 관련이 있는 것으로 생각되었다. 따라서 PMI 추정 시 사체의 노출 정도가 반드시 고려되어야 한다고 생각되었다. This study was carried out to offer forensic entomological evidence to estimate the post mortem interval (PMI) based on the arthropod succession in pig carrions and carrion decomposition patterns varying with the exposed extent of the carrions. Four carrions, exposed, wrapped, covered or shaded, were placed in an open grassland near the Nakdong-river in Busan in August, 2010. It was found that the first visiting insect was Chrysomyia megacephala among a total of 20 species of 15 families belonging to 7 orders of Insecta, and that four species were useful indicators of the decomposition stage of the carrion: C. megacephala for I~V stages; a species of Sepsidae, Creophilus maxillosus and a species of Carabidae for III~V stages. It was also found that the more the exposed extent of exposure of carrions, the higher the rate of decomposition of carrions, i. e. the time for decomposition of carrions were 7days for the exposed carrion, 10days for the covered one, 13days for the shaded one, and 15days for the wrapped one. This result seems to be related to the differences in the weight loss of carrions caused by strong rains during the research period and by the accessibility of insects to the carrions; both are strongly affected by the exposed extent of the carrions. Accordingly, it was suggested that the exposed extent of the carrions must be taken into consideration to estimate the PMI.

Estimating the pre-appearance interval from temperature in Necrodes littoralis L. (Coleoptera: Silphidae)

While estimating post-mortem interval from entomological evidence it is useful to divide it into two separate intervals: the pre-appearance interval (PAI) and the development interval in the case of immature insects and PAI and the presence interval in the case of adult insects. An accurate estimate of PAI is critically important particularly in the case of those insects which appear on remains late in decomposition. In this paper the possibilities of PAI estimation from temperature are evaluated in late-arriving, forensically important carrion beetle Necrodes littoralis. The relationship between PAI of adult and larval N. littoralis and temperature was modelled by using results of succession experiments in forests of Central Europe. In both stages PAI was found to be strongly, inversely dependent on mean daily ground level temperatures averaged for the duration of PAI. Several methods of PAI estimation were proposed and their accuracy was initially evaluated with external successional data.

Polymerase Chain Reaction Pool Screening Used To Compare Prevalence of Infective Black Flies in Two Onchocerciasis Foci in Northern Sudan

Onchocerciasis remains an important debilitating disease in many areas of Africa, including Sudan. The status of infection transmission in 2007 was assessed in the vectors of two disease foci in Sudan: Abu Hamed in northern Sudan, which has received at least 10 years of annual treatment and Galabat focus in eastern Sudan, where only minor, largely undocumented treatment activity has occurred. Assessment of more than 30,000 black flies for Onchocerca volvulus infectious stage L3 larvae by using an O-150 polymerase chain reaction protocol showed that black fly infectivity rates were 0.84 (95% confidence interval = 0.0497-1.88) per 10,000 flies for Abu Hamed and 6.9 (95% confidence interval = 1.1-16.4) infective flies per 10,000 for Galabat. These results provide entomologic evidence for suppressed Onchocerca volvulus transmission in the Abu Hamed focus and a moderate transmission rate of the parasite in the Galabat focus.

Insects found on a human cadaver in central Italy including the blowfly Calliphora loewi (Diptera, Calliphoridae), a new species of forensic interest

In the case of unidentified bodies the estimation of the period since death or of the season of death plays an important role to focus the attention on a reduced number of people among the ones reported missing. Forensic entomology can be one of the most important methods for these estimations, as occurred in this case. Flies are typically the first insects to colonize a dead body. The case reported here concerns the colonisation by insects of a male body in advanced decay found during the winter in Central Italy. This case is of particular interest as few data are available on the entomological evidence in the cold season. In particular, in this case we recovered Calliphora loewi (Calliphoridae), a species never collected before on dead bodies in Southern Europe. Larvae of the black soldier fly Hermetia illucens (Stratiomyidae), pupae and larvae belonging to genus Hydrothea (Muscidae), and Necrobia rufipes (Cleridae) specimens were also collected. The estimated PMI enabled identification of the cadaver, confirmed by DNA analysis.