Wing morphometrics for the identification of Nearctic and Palaearctic Piophilidae (Diptera) of forensic relevance

Morphological and molecular characterization of puparia of Piophilidae species of forensic relevance

Piophilidae are a small family of Diptera with a worldwide distribution and which are historically associated with human activities. In addition to their economic importance, piophilid larvae can also be of medical and legal relevance. Within a medicolegal context, piophilids are frequently associated with cadavers in advanced stages of decomposition, thus being potentially useful forensic indicators and they have been reported also from archaeo-funerary contexts. An accurate species identification is therefore an essential prerequisite to ensure the reliable analysis of insect material in medical, forensic and archaeological investigations. Identification of the adult piophilid flies is possible because of the availability of identification keys, in contrast immature insects, especially puparia, have been poorly investigated and described. In this paper, puparia of 11 species of forensic interest (Piophila casei, Piophila megastigmata, Parapiophila atrifrons, Parapiophila flavipes, Parapiophila vulgaris, Protopiophila litigata, Liopiophila varipes, Prochyliza nigrimana, Prochyliza xanthosoma and Stearibia nigriceps in subtribe Piophilina and Centrophlebomyia furcata in subtribe Thyreophorina) are described and a molecular analysis, based on the COI sequencing, is presented to show the potential of the molecular approach in their identification.

Honey bee (Apis mellifera) wing images: a tool for identification and conservation

BACKGROUND

The honey bee (Apis mellifera) is an ecologically and economically important species that provides pollination services to natural and agricultural systems. The biodiversity of the honey bee in parts of its native range is endangered by migratory beekeeping and commercial breeding. In consequence, some honey bee populations that are well adapted to the local environment are threatened with extinction. A crucial step for the protection of honey bee biodiversity is reliable differentiation between native and nonnative bees. One of the methods that can be used for this is the geometric morphometrics of wings. This method is fast, is low cost, and does not require expensive equipment. Therefore, it can be easily used by both scientists and beekeepers. However, wing geometric morphometrics is challenging due to the lack of reference data that can be reliably used for comparisons between different geographic regions.

FINDINGS

Here, we provide an unprecedented collection of 26,481 honey bee wing images representing 1,725 samples from 13 European countries. The wing images are accompanied by the coordinates of 19 landmarks and the geographic coordinates of the sampling locations. We present an R script that describes the workflow for analyzing the data and identifying an unknown sample. We compared the data with available reference samples for lineage and found general agreement with them.

CONCLUSIONS

The extensive collection of wing images available on the Zenodo website can be used to identify the geographic origin of unknown samples and therefore assist in the monitoring and conservation of honey bee biodiversity in Europe.

Wing measurements are a possible tool for the identification of European forensically important Sarcophagidae

The flesh flies are a group of insects well known for their forensic importance. Reliable identification of these flies relies on the use of either molecular markers or the morphology of the male genital apparatus. Identification of female flesh flies is more time consuming and less reliable than their male counterparts. This is particularly problematic for forensic entomology practitioners, because female flesh flies are more abundant than males in carrion arthropod assemblages. As such, it is critical that alternative methods for flesh fly identification are established that are equally effective for both sexes. One promising technique is the use of wing measurements, which have been shown to be reliable for the identification of some groups of necrophagous Diptera from several geographical regions. We applied this method to the European Sarcophagidae for the first time, using a dataset of 881 specimens representing 29 species and 5 genera. Species identifications were based on 15 landmarks located at wing vein junctions. We also combined our results with data from previous studies of Calliphoridae and Muscidae which utilised the same methodology, enabling the testing of family level identification using wing morphometrics. Species identifications using wing measurements had varied success. While some species were successfully identified without error, others, particularly from the genus Sarcophaga, were often misclassified. Notably, in several species wing measurements successfully identified both males and females. The results presented here suggest that wing measurements are a promising complementary method to other methods for the identification of necrophagous Sarcophagidae especially in material unsorted at the family level. It can also be used to double check identification performed by a taxonomist using traditional methods.

First report of the forensically important fly, Stearibia nigriceps (Diptera: Piophilidae) in South Korea: Confirmation of specimens from human corpses based on cytochrome c oxidase subunit I barcodes

Piophilidae are a relatively small family of Diptera that is frequently associated with cadavers at advanced stages of decomposition and are, therefore, considered potentially useful forensic indicators. However, their use in forensic investigations is typically hampered by a deficiency in reliable identification tools. This is particularly evident in countries such as South Korea, where forensic entomology is still in its infancy and the diversity of forensically relevant insect taxa remains largely undocumented. In the present study, we used cytochrome c oxidase subunit I (COI) barcodes to identify samples of piophilid larvae collected during medicolegal investigations performed in South Korea. A total of 174 COI sequences were obtained and have been made publicly available, thus augmenting the reference barcode library for forensically important Piophilidae species. Of the 174 sequenced samples, 172 were identified as Stearibia nigriceps (Meigen), whereas the two remaining samples may represent a previously unsequenced piophilid species. Stearibia nigriceps is recorded from South Korea for the first time, and our results suggest that it might be a particularly relevant forensic indicator in certain case types and scenarios in that country. The findings of this study highlight the utility of COI barcodes for achieving accurate identification of entomological samples, even by non-specialist forensic practitioners. They also contribute to the further development and consolidation of forensic entomology in South Korea and eastern Asia.

Wing morphometrics for identification of forensically important blowflies (Diptera: Calliphoridae) in Iberian Peninsula

Calliphoridae is a family of Diptera of great forensic interest because some of its species belong to the sarcosaprophagous diptera community, as their larvae are necrophagous or necrophilous. In the Iberian Peninsula there are six species that stand out, as they are the first insects to arrive at carrion: Calliphora vicina, Calliphora vomitoria, Lucilia sericata, Lucilia caesar, Chrysomya albiceps and Chrysomya megacephala. To differentiate among these blowflies, we compared the value of using traditional and geometric morphometrics by performing a morphometric analysis of the wings (shape and size). A total of 600 individuals were considered, segregated by species and sex equally. Seventeen landmarks per wing were recognized, and then centroid size and shape analyses were performed using geometric morphometrics, and size using traditional morphometrics, to identify species and sex. The results showed differences in shape among the species and it was found that landmarks 2 to 11 were the most variable, while the landmarks located at the base of the wings were relatively stable. However, according to both traditional and geometric morphometrics, no significant differences were found among species in wing size (Calliphora vicina, Chrysomya megacephala and Lucilia caesar were indistinguishable), but females were larger than males (except for the two Chrysomya species). Our results indicate that the use of geometric morphometrics to analyze wing configuration (shape) is an easy-to-use tool that helps to distinguish among common blowfly species of forensic importance.