Use of DNA sequences to identify forensically important fly species and their distribution in the coastal region of Central California

Molecular differentiation analysis of ten putative species of Fannia (Diptera: Fanniidae) collected in carrion-baited traps from Colombia

The genus Fannia is the most representative of the Fannidae family of true flies with worldwide distribution. Some species are attracted to decomposing materials and live vertebrate animals, which makes them important in forensics, medical and veterinary fields. However, identifying Fannia species can be difficult due to the high similarity in the external morphology of females and limited descriptions and morphological keys. Herein, molecular markers could provide a complementary tool for species identification. However, molecular identification has still limited application since databases contain few data for neotropical species of Fannia. This study assessed the potential of two molecular markers, the COI-3' region and internal transcribed spacer 2 (ITS2), to differentiate 10 putative species of the genus Fannia from Colombia using distance-based and tree-based approaches. The partial ITS2 and/or COI-3' regions allowed molecular diagnosis of six species, while pairs of species Fannia colazorrensis + F. dodgei and F. laclara + F. aburrae are conflicting. Although these results might suggest that conflicting pair species are conspecific, consistent morphological differences between males do not support this hypothesis. The lack of differentiation at the nuclear and mitochondrial molecular markers for the conflicting species may be due to incomplete evolutionary lineage separation, hybridization, or introgression events. In addition, sexual selection on male morphological traits before species-specific differences in molecular markers emerge may partially explain the results. Our study provides a valuable dataset to identify and confirm some Fannia species molecularly. Further, they could be used to associate females and immature stages with their conspecifics as a baseline to deep into their biology, ecology, distribution and potential applications in forensic and medico-veterinary entomology.

Mejoramiento de un método no comercial para la extracción de ADN de moscas de interés médico-legal

La obtención de ADN de moscas de interés médico-legal es de relevancia para una variedad de aplicaciones. Aunque existen métodos de extracción comerciales de ADN, su uso rutinario es limitado, en algunos escenarios. En este contexto, el uso de métodos no comerciales constituye una alternativa; sin embargo, su optimización es clave para mejorar el flujo de trabajo y los resultados. Este trabajo evaluó el impacto de variaciones a un método de precipitación salina sobre la concentración y la pureza del ADN recuperado. No se encontraron diferencias significativas en la concentración de ADN extraído entre los diferentes tiempos de incubación, probados durante la fase de extracción, mientras que el incremento en el volumen de etanol absoluto, en la fase de precipitación de ADN, mejoró significativamente la concentración de ADN obtenido. Las modificaciones propuestas reducen el tiempo de ejecución y la concentración de ADN obtenido comparado con el protocolo original.

Molecular identification of forensically important fly species in Spain using COI barcodes

Species identification with DNA barcodes has been proven to be effective on different organisms and, particularly, has become a routinely used and quite accurate tool in forensic entomology to study necrophagous Diptera species. In this study, we analysed 215 specimens belonging to 42 species of 17 genera, from 9 different Diptera families. Flies were collected in 39 Spanish localities of the Iberian Peninsula sampled across three years in the four seasons. Intraspecific variation ranged from 0 to 2.46% whereas interspecific variation fluctuated from 3.07 to 14.59%, measuring 651 pb of the cytochrome oxidase subunit one (COI) gene. Neighbour-Joining analysis was carried out to investigate the molecular identification capabilities of the barcoding region, recovering almost all species as distinct monophyletic groups. The species groupings were generally consistent with morphological and molecular identifications. This work, which is the first with this intensive and extensive sampling in this area, shows that the COI barcode is an appropriate marker for unambiguous identification of forensically important Diptera in Spain.

Molecular Identification of the Carrion Beetles (Coleoptera) in Selected Regions of Saudi Arabia

Geographical regions have a major effect on the arrival times of different insect species on carrion. This means that data generated in one region should not be used to determine time of death in a different region. In the present study, we demonstrate the effect of geographical location on the diversity of carrion beetles in Saudi Arabia, whereas the mitochondrial cytochrome c oxidase subunit I (mtCOI) barcodes were used as a marker for molecular identification of the carrion beetles at a dry stage on sheep carrion. We analyzed 819 adult beetles belonging to nine species originating from Riyadh (609 beetles), Jazan (157 beetles), and Arar (53 beetles). In Riyadh, results showed the presence of six species belonging to three different families. On the other hand, in Jazan five species belonging to four families were collected. From Arar, five species belonging to three families were collected. By comparing between individuals of the same species from different regions, individuals of Necrobia rufipes DeGeer (Coleoptera: Cleridae) showed the highest intraspecific variations 0-20%, while individuals of Saprinus splendens Paykull and Saprinus semistriatus Scriba (Coleoptera: Histeridae) showed the lowest intraspecific variations 0-1%. Interspecific variability was also measured between collected and identified species, with differences revealed to be in the range of 3.8-29.8%. The results are important from an ecological point of view and for Medico-Legal Forensic Entomology.

The Application of COI Gene for Species Identification of Forensically Important Muscid Flies (Diptera: Muscidae)

Muscid Flies (Diptera: Muscidae) are of great forensic importance due to their wide distribution, ubiquitous and synanthropic nature. They are frequently neglected as they tend to arrive at the corpses later than the flesh flies and blow flies. Moreover, the lack of species-level identification also hinders investigation of medicolegal purposes. To overcome the difficulty of morphological identification, molecular method has gained relevance. Cytochrome c oxidase subunit I (COI) gene has been widely utilized. Nonetheless, to achieve correct identification of an unknown sample, it is important to survey certain muscid taxa from its geographic distribution range. Accordingly, the aim of this study is to contribute more geographically specific. We sequenced the COI gene of 51 muscid specimens of 12 species, and added all correct sequences available in GenBank to yield a total data set of 125 COI sequences from 33 muscid species to evaluate the COI gene as a molecular diagnostic tool. The interspecific distances were extremely high (4.7-19.8%) in either the standard barcoding fragment (658 bp) or the long COI sequence (1,019-1,535 bp), demonstrating that these two genetic markers were nearly identical in the species identification. However, the intraspecific distances of the long COI sequences were significantly higher than the barcoding region for the conspecific species that geographical locations vary greatly. Therefore, genetic diversity presented in this study provides a reference for species identification of muscid flies. Nevertheless, further investigation and data from more muscid species are required to enhance the efficacy of species-level identification using COI gene as a genetic marker.

New Distribution Record for Lucilia cuprina (Diptera: Calliphoridae) in Indiana, United States

Determining range expansion for insect species is vital in order to evaluate their impact on new ecosystems and communities. This is particularly important for species which could be potentially harmful to humans or domestic animals. Lucilia cuprina Wiedemann (Diptera: Calliphoridae) can act as a facultative ectoparasite and has an extensive history as the primary inducer of sheep-strike in Australia, New Zealand, and Africa. We present here the first record of this species in Indiana, United States. Lucilia cuprina's range expansion northward in the United States may be indicative of changing environmental conditions conducive to the proliferation of this species into historically cooler climates. The presence of this species could significantly impact forensic death investigations utilizing dipteran larvae to estimate a minimum postmortem interval. If range expansion of this species is not taken into account by a forensic entomologist (especially if L. cuprina is not known previously in their region), an inaccurate minimum postmortem interval (PMIMIN) estimation may be made, given the differences in development times for both species. Therefore, the range expansion of this fly could have large impacts for many different entomological disciplines.

Identification of Forensically Important Blow Flies (Diptera: Calliphoridae) in China Based on COI

Blow flies are among the most important insects in forensic entomology casework. Identification of blow fly species can be a time consuming and difficult task, especially at their early development stages. Present DNA-based technologies provide a promising identification method for these forensically important calliphorids. The cytochrome oxidase subunit I (COI) sequence has been applied as a suitable DNA marker in calliphorid identification for many years; however, limitation exists in using short sequence to determine genetically close species. In this study, COI long sequences were utilized in species-level identification. Seventy-two specimens were collected from 27 locations across 22 Chinese provinces, and unambiguously determined as 16 species under seven genera of Calliphoridae. Analysis of long mitochondrial COI sequence (1,021-1,382 bp) data from forensically relevant blow flies collected in the inland region of China provided a reliable marker for accurate identification. Our data provide genetic diversity and reference for global forensic-related blow fly species identification, and conductive meaning on future utilization of Chinese calliphorids used in forensic entomological practice.

First Report of Necrophagous Insects on Human Corpses in Riyadh, Saudi Arabia

Necrophagous species of insects provide useful complementary data to estimate the postmortem interval in forensic cases. Here, for the first time, we report on insect specimens collected from human corpses in Riyadh, Kingdom of Saudi Arabia. During the study, 14 beetle larvae were collected from the outdoor corpse (case report one) and five flies and seven beetles were collected from the indoor corpse (case report two). Sequencing was performed to study the mitochondrial DNA (mtDNA) as the prospective basis of an identification technique. The sequencing focused on a section of the cytochrome oxidase I encoding region of mtDNA. Two beetle species, Dermestes frischii (Kugelann) and Dermestes maculatus (De Geer) (Coleoptera: Dermestidae), and one fly species, Chrysomya albiceps (Wiedemann) (Diptera: Calliphoridae), were identified. These results will be instrumental in the implementation of a Saudi database of forensically relevant insects.

Ultrastructure analysis of the immature stages of Ravinia belforti (Diptera: Sarcophagidae), a species of medical-veterinary and forensic importance, by scanning electron microscopy

The postmortem interval is related to the age of immature species of flies found on corpses and can be estimated using data available in the literature on the biology of the species. The flesh fly Ravinia belforti is a carrier of enteric pathogens that can affect human and animal health as well as being of forensic importance. As the morphology of many immature Sarcophagidae is unknown, these immature forms must be collected and characterized after the emergence of the adult male. Here we describe and analyze the morphological characteristics of the larvae stages L1, L2, L3 and the puparium of R. belforti by scanning electron microscopy (SEM). Ten specimens of each stage were analyzed. Larvae of R. belforti follow the typical muscoid vermiform pattern with 12 segments. The anterior region is pointed, while the posterior region is thicker. The spines of the cephalic collar are flattened and with double, triple or quadruple points, different from the spines along the body that only have a single point. In L2, the anterior spiracle is present with a varying number of papillae (16-22), differing from other species. The posterior spiracles are located within the peritreme. The spiracular cavity is internalized in the posterior region, following the pattern that differs Sarcophagidae from other families. L3 features more visible and developed spines around the cephalic collar, getting thicker and denser near to the first thoracic segment. Puparium is similar to other species of Sarcophagidae. This paper presents important data on this family which has both health and forensic importance. Furthermore, R. belforti shows significant differences from other species of Sarcophagidae.

Use of handheld X-ray fluorescence as a non-invasive method to distinguish between Asian and African elephant tusks

We describe the use of handheld X-ray fluorescence, for elephant tusk species identification. Asian (n = 72) and African (n = 85) elephant tusks were scanned and we utilized the species differences in elemental composition to develop a functional model differentiating between species with high precision. Spatially, the majority of measured elements (n = 26) exhibited a homogeneous distribution in cross-section, but a more heterologous pattern in the longitudinal direction. Twenty-one of twenty four elements differed between Asian and African samples. Data were subjected to hierarchical cluster analysis followed by a stepwise discriminant analysis, which identified elements for the functional equation. The best equation consisted of ratios of Si, S, Cl, Ti, Mn, Ag, Sb and W, with Zr as the denominator. Next, Bayesian binary regression model analysis was conducted to predict the probability that a tusk would be of African origin. A cut-off value was established to improve discrimination. This Bayesian hybrid classification model was then validated by scanning an additional 30 Asian and 41 African tusks, which showed high accuracy (94%) and precision (95%) rates. We conclude that handheld XRF is an accurate, non-invasive method to discriminate origin of elephant tusks provides rapid results applicable to use in the field.