Species diversity and tissue specific dispersal of necrophagous Diptera on human bodies

Abstract

In forensic entomology, many studies analyze fly activity and succession on dead bodies by using pig cadavers and a variety of small baited traps. Data on real human bodies are very rare. To address this shortcoming, we analyzed the fly fauna of 51 human bodies in Germany. Sex, age, place of discovery, and presumed time of death were noted. Larvae were sampled during autopsy according to body region or tissue. For every infested region, the total number of fly larvae were estimated and classified into categories of 1-10, 11-50, and 50+. All samples were identified to the species level. Besides a descriptive analysis of their occurrence patterns, a categorical PCA was performed, and multispecies generalized linear models and a latent variable model were run. Our results highlight the most forensically important blow flies on human bodies in Central Europe (Lucilia sericata, L. ampullacea, Phormia regina, Calliphora vicina); prove, for the first time, the general transferability of species lists based on succession studies on pig cadavers; recommend a certain set of species, such as the so-far neglected L. ampullacea, for future developmental studies; and reveal competitive occurrence of up to six species on the same body as a potential factor of influence. Assignment to a certain body region was often possible and our data clearly indicate certain tissues, e.g. brain, as of high interest for future developmental studies. Focusing on real scenario settings helps direct research to forensically relevant questions and appraises the plausibility of vital laboratory studies.

Keywords: Body region; Distribution; Diversity; Flies; Forensic entomology; Human cadaver.