DNA Barcoding Identifies Unknown Females and Larvae of Fannia R.-D. (Diptera: Fanniidae) from Carrion Succession Experiment and Case Report

Simple Summary Insects are frequently attracted to animal and human cadavers, usually in large numbers. The practice of forensic entomology can utilize information regarding the identity and characteristics of insect assemblages on dead organisms to determine the time elapsed since death occurred. However, for insects to be used for forensic applications it is essential that species are identified correctly. Imprecise identification not only affects the forensic utility of insects but also results in an incomplete image of necrophagous entomofauna in general. The present state of knowledge on morphological diversity and taxonomy of necrophagous insects is still incomplete and identification of immature and female forms can be extremely difficult. In this study, we utilized molecular identification methods to link conspecific sexes and developmental stages of forensically important flies. We identified larvae and females of flies collected from animal and human cadavers which otherwise were morphologically unidentifiable. The present study fills a gap in taxonomy of flies and provides data facilitating application of new species as forensic indicators. Application of available keys to European Fanniidae did not facilitate unequivocal species identification for third instar larvae and females of Fannia Robineau-Desvoidy, 1830 collected during a study of arthropod succession on pig carrion. To link these samples to known species, we took the advantage of molecular identification methods and compared newly obtained cytochrome oxidase subunit I (COI) barcode sequences against sequences deposited in reference databases. As an outcome of the results obtained, we describe for the first time a third instar larva of Fannia nigra Malloch, 1910 and Fannia pallitibia (Rondani, 1866) and a female of Fannia collini d'Assis-Fonseca, 1966. We provide combinations of characters allowing for discrimination of described insects from other Fanniidae. We provide an update for the key by Rozkosny et al. 1997, which allows differentiation between females of F. collini and other species of Fanniidae. Additionally, we provide a case of a human cadaver discovered in Southern Poland and insect fauna associated with it as the first report of F. nigra larvae developing on a human body.

Automated summary

Forensic entomology is the practice of utilizing insects on dead organisms to determine time of death, with molecular identification methods allowing for accurate identification of fly species and developmental stages. This study fills gaps in fly taxonomy and provides updated information on key characteristics for species differentiation.