Forensic entomology: a new hypothesis for the chronological succession pattern of necrophagous insect on human corpses

Abstract

Forensic entomology can help to estimate the time elapsed since death, by studying the necrophagous species collected on a cadaver and its surroundings. The determination of the so- called post mortem interval (PMI or period of first oviposition) is based on the development time of necrophagous dipterans and on the chronological pattern of insects’ succession on the corpse throughout the decaying process. In the present study, authors investigated this succession by the analysis of the database of the Department of Forensic Entomology of the French Gendarmerie over 12 years (1992–2003) in order to propose a new approach and a new hypothsesis of the dynamic of necrophagous-insects’ populations present on a human cadaver over time. For all treated cases, the presence/absence and the oldest development stage of the species were recorded. Data were analyzed by statistical and Wagner parsimony methods. The statistic results allowed the association of groups of species with typical developmental stages. The Wagner parsimony analysis showed that the dynamic of the necrophagous insect population present on a cadaver could be characterised by specific species. Together, they allowed establishing hypotheses of succession of necrophagous insects on human cadavers over time that could be usefull in the PMI estimation.