An empirical comparison of decomposition and fly colonisation of concealed carcasses in the Old and New World

The level of exposure or concealment of a cadaver is known to have an important impact on insect colonisation and decomposition but has been the subject of few investigations. In the present study, 30 pig carcasses were stored in three different types of containers (suitcases, trashcans and drums) with different levels of access for necrophagous insects at two different geographic locations for 100 days. The decomposition proceeded in a similar way in both geographic locations in all three types of container. Both in trashcans and suitcases, the decomposition process was characterised by bones and greasy, brown decomposition fluids left in the containers and an overall moist decomposition. In contrast, decomposition in the drums was characterised by a long bloating phase followed by a slow transition from bloated to deflation. Tissue and the carcasses as a whole were still present till the end of the experiment. Insect occurrence patterns and species composition on suitcases and trashcans were similar for both countries. Mainly flies and some beetles were present in suitcases and trashcans until day 45, with blow flies (Diptera: Calliphoridae) dominating the fauna. There was no insect colonisation in the drums. Our study contributes to the knowledge about insect accessibility of concealed cadavers and the impact of concealment on the speed and type of decomposition. It clearly shows that the degree of exposure of a cadaver is a key factor in decomposition and insect colonisation, which had a larger effect here than the biogeographical location.