Query: forensic entomology

title: Pigs vs people: the use of pigs as analogues for humans in forensic entomology and taphonomy research
abstract: Most studies of decomposition in forensic entomology and taphonomy have used non human cadavers. Following the recommendation of using domestic pig cadavers as analogues for humans in forensic entomology in the 1980s, pigs became the most frequently used model cadavers in forensic sciences. They have shaped our understanding of how large vertebrate cadavers decompose in, for example, various environments, seasons and after various ante or postmortem cadaver modifications. They have also been used to demonstrate the feasibility of several new or well established forensic techniques. The advent of outdoor human taphonomy facilities enabled experimental comparisons of decomposition between pig and human cadavers. Recent comparisons challenged the pig as analogue claim in entomology and taphonomy research. In this review, we discuss in a broad methodological context the advantages and disadvantages of pig and human cadavers for forensic research and rebut the critique of pigs as analogues for humans. We conclude that experiments using human cadaver analogues (i.e. pig carcasses) are easier to replicate and more practical for controlling confounding factors than studies based solely on humans and, therefore, are likely to remain our primary epistemic source of forensic knowledge for the immediate future. We supplement these considerations with new guidelines for model cadaver choice in forensic science research.

title: Book review: Byrd J.H. Tomberlin J.K. (eds) 2020: Forensic Entomology: The Utility of Arthropods in Legal Investigations. 3rd Ed.
abstract: Byrd J.H. Tomberlin J.K. (eds) 2020: Forensic Entomology: The Utility of Arthropods in Legal Investigations. 3rd Ed. CRC Press, Boca Raton, FL, xxxiv 585 pp. ISBN 978 0 815 35016 3 (hardback) 978 0 815 35020 0 (paperback) 978 1351163767 (ebook) Price USD 120.00 (hardback) USD 74.99 (paperback) USD 67.49 (e book)

title: Development of Necrobia rufipes (De Geer, 1775) (Coleoptera: Cleridae) under constant temperatures and its implication in forensic entomology.
abstract: After the death of humans or animals, the odors released at different stages of decay attract various insects, and other arthropods, to the corpses. Therefore, the development of insects, and other arthropods present on corpses, can be assessed to estimate the minimum postmortem interval since death. In general, necrophagous blow flies are the insects that first colonize corpses. With progressing decay, other necrophagous and predatory insects arrive at the corpses, which will develop on or around these either by feeding directly on the corpses or by prey on other immature insects. Beetles (Coleoptera) mainly arrive at the corpses during the later stages of decay, and play important roles in cases with longer postmortem intervals. Necrobia rufipes (De Geer, 1755) (Coleoptera: Cleridae) is an important stored product species with world wide distribution. Moreover, it is also a forensically important insect species. At temperatures of 22, 25, 28, 31, 34, and 36degC 0.5degC) the developmental periods from egg to adult were 113.20+ 2.96, 66.16+ 3.22, 50.61+ 1.95, 38.26+ 2.48, 37.97+ 2.40, and 31.20+ 2.11 days, respectively. In vivo measurements obtained the morphological indexes of larvae. The growth curve and the equation of the relationship between development time, body lengths, and mesonotum widths were simulated. The isomorphen diagram model, the isomegalen diagram model, and the thermal summation model were established. In addition, the widths of head capsules and pronota of larvae at different instars were determined by cluster analysis. Classifiers were created and validated by linear discriminant analysis.

title: Forensic entomology for the investigator

title: An Evaluation of Differentially Spliced Genes as Markers of Sex for Forensic Entomology
abstract: Blow flies (Calliphoridae) are important medically and economically and are commonly used in forensics as temporal markers in death investigations. While phenotypic traits in adult flies can be sexually dimorphic, sex identification in immatures is difficult. Consequently, little is known about how sex may result in developmental disparities among sexes even though there are indications that they may be important in some instances. Since genetic mechanisms for sex are well studied in model flies and species of agricultural and medical importance, we exploit the sex specifically spliced genes transformer (tra) and doublesex (dsx) in the sex determination pathway to optimize a sex identification assay for immatures. Using known primer sets for tra and with a novel one for dsx, we develop PCR assays for identifying sex in four forensically relevant Calliphoridae species: Lucilia sericata (Meigen) Lucilia cuprina (Wiedemann) Cochliomyia macellaria (Fabricius) and Chrysomya rufifacies (Macquart) and evaluated their performance. Band detection rates were found to range from 71 to 100% call rates ranged from 90 to 100% and no error was found when bands could be called. Such information is informative for purposes of testimony and in preparation for development studies. The developed assays will assist in further differentiating sexually dimorphic differences in development of the Calliphoridae and aid in more accurately estimating insect age when age predictive markers (size, development time, molecular expression) are sexually dimorphic.

title: A bibliometric analysis of forensic entomology trends and perspectives worldwide over the last two decades (1998 2017)
abstract: Through bibliometric analysis, this study aimed to reveal worldwide research productivity and trends in forensic entomology over the last two decades (1998 2017) As "forensic entomology" is yet to be established as a Medical Subject Headings term, we used "forensic entomology" and "legal entomology" as topics in Web of Science Core Collection, Medline, and PubMed searches. Two independent investigators retrieved and evaluated 3165 articles. After determining the cutoff for publication year and excluding repeated or irrelevant articles, 1087 articles remained for analysis. In terms of papers published, the United States was the most productive among the 136 countries (and disputed regions) that contributed to forensic entomological research. Among the 179 journals that published all articles, two were considered core journals based on Bradford's Law (i.e. the two journals published the majority of relevant articles) Most studies focused on the order Diptera and family Calliphoridae. The most common topics were estimation of postmortem interval and species identification.

title: DNA Barcoding in Forensic Entomology Establishing a DNA Reference Library of Potentially Forensic Relevant Arthropod Species
abstract: Throughout the years, DNA barcoding has gained in importance in forensic entomology as it leads to fast and reliable species determination. High quality results, however, can only be achieved with a comprehensive DNA barcode reference database at hand. In collaboration with the Bavarian State Criminal Police Office, we have initiated at the Bavarian State Collection of Zoology the establishment of a reference library containing arthropods of potential forensic relevance to be used for DNA barcoding applications. CO1 5P' DNA barcode sequences of hundreds of arthropods were obtained via DNA extraction, PCR and Sanger Sequencing, leading to the establishment of a database containing 502 high quality sequences which provide coverage for 88 arthropod species. Furthermore, we demonstrate an application example of this library using it as a backbone to a high throughput sequencing analysis of arthropod bulk samples collected from human corpses, which enabled the identification of 31 different arthropod Barcode Index Numbers.

title: Intrapuparial Development of Hemilucilia semidiaphana (Diptera: Calliphoridae) and Its Use in Forensic Entomology
abstract: In forensic entomology, the minimum postmortem interval (PMImin) estimative is usually based on the oldest immature recovered from a local of death. The time spent by fly immatures in the intrapuparial period comprises more than 50% of their complete life cycles. An accurate estimate of the duration of this period will improve PMImin estimates. The blow fly Hemilucilia semidiaphana (Rondani 1850) was found in six criminal cases in the city of Curitiba. Even though there is data on the morphology of the larval instars and developmental rate of H. semidiaphana, the intrapuparial period has not been investigated. Here, we provide a detailed description of the intrapuparial morphological changes of H. semidiaphana, which might be useful to estimate minimum PMI. Samples of H. semidiaphana in the intrapuparial period were obtained from immatures reared on an artificial diet in incubators adjusted to 25degC or 20degC temperature regimes. Blow fly puparia of H. semidiaphana were fixed at intervals of 3 and 6 h until emergence of the adult. The external morphological traits of sampled immatures were analyzed using light microscopy. Our analysis of the intrapuparial period of H. semidiaphana provided 21 traits from which nine were age informative. These nine characteristics divide the developmental time (144 h at 25degC and 192 h at 20degC) into smaller sections. The developmental data provided, together with the time line allows a practical way to make interspecific comparisons as well as to estimate the age of H. semidiaphana based on the intrapuparial development.

title: Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae) development by landmark based geometric morphometrics of cephalopharyngeal skeleton: a preliminary assessment for forensic entomology application
abstract: BackgroundConsidering the practicality of geometric morphometrics which could discriminate insect species, this application was extended to the analysis of blow fly larval growth based on cephalopharyngeal skeleton. In forensic entomology, cephalopharyngeal skeleton plays a crucial role in species identification but the morphometric information of this part is scarce. In this study, Chrysomya megacephala (Fabricius, 1794) was reared in two study replicates in natural conditions and samplings were conducted at fixed daily intervals. Cephalopharyngeal skeletons were removed from larvae and mounted on glass slides. Images were obtained from the specimens; digitized and geometric morphometric analysis on C. megacephala cephalopharyngeal skeletons was performed with MorphoJ software based on the ordination of five landmarks. The assessments of this analysis were based on centroid size measurements, visualization on the landmarks displacements, classification of the relative landmarks by using canonical variate analysis, and ontogenetic allometry determination.FindingsCentroid size was strongly correlated with developmental time (p 0.05) and significantly different between daily intervals (p 0.05) Ontogenetic allometric effect based on multivariate regression on Procrustes coordinates and centroid size was significant (p 0.0001) indicating that shape was influenced by growth (60.3% Disposition occurred on all landmarks during development and was further discriminated based on age groups.ConclusionsOther than discriminating between species, geometric morphometrics was found to be practical to visualize larval growth based on cephalopharyngeal skeletons which can be useful in forensic entomology.

title: Post embryonic development of Chrysomya putoria (Diptera: Calliphoridae) in swine and bovine tissues in South America: implications for forensic entomology
abstract: Necrophagous diptera are used in forensic entomology to measure the post mortem interval (PMI) of cadavers. PMI estimates based on fly larvae, however, can be inaccurate when larval development is retarded, or accelerated, by the nutritional composition of the cadaveric tissue. We compared the post embryonic development of Chrysomya putoria (Wiedemann, 1830) on different tissues of pigs and cows. Forty newly hatched fly larvae per treatment were placed on 60 g of the following swine tissues: liver (T1) swine lung (T2) swine heart (T3) swine muscle (T4) bovine heart (T5) bovine lung (T6) and bovine muscle (T7) There were four replicates/treatment. Experiments were conducted in controlled conditions (28degC day/26degC night, RH 70% 10% and 12 h of photophase) Fly larvae reared on swine liver took longer to develop (5.2 days) than flies reared on other substrates (from 3.5 to 4.5 days) and this difference was statistically significant. The total duration of development on swine liver (T1) was significantly slower (8.7 days) when compared to the other treatments. Larvae reared on swine lungs (T2) were significantly heavier in the third instar x 61.2 mg) than larvae reared on swine liver (T1) swine muscle (T4) bovine lung (T6) and bovine muscle (T7) Total larval survival was high (above 76% in all treatments except for T1 (66% There was no deviation from the expected adult sex ratio, and the percentage of abnormalities remained within the expected range. These results reinforce the idea that, to achieve greater accuracy in PMI estimates, the type of tissue on which the larvae develops needs to be taken into account.