The insects colonisation of buried remains

Abstract

In our society, burial of a deceased person is a common habit in a normal situation. In opposition, manmade burial by authors of homicide and/or their accomplices to hide the body of their victim is more seldom. Exhumation of a buried corpse can be ordered by legal decision (second expert conclusion). It can also be accidental or required by authorities for investigation purposes (mass grave) or identification of victims (natural disaster or accident). Location of an illegal grave is a hard task and the excavation needs to apply adapted techniques and to gather different specialists (forensic investigators, pathologists, dentists, botanists, entomologists, etc.). Decomposition of corpses is affected by burial environment (conservation, mummification, adipocere formation, etc.) because of climatic, edaphic and biological parameters. It is well known that the decomposition process in soil is vastly different than on the surface, due to different parameters. Accessibility of the necrophagous entomological fauna to the body is either disturbed (arrival delayed) or inhibited. The composition of the insects' population can be strongly modified in addition to the duration of the life cycle. When colonisation is possible, the number of insects and the diversity of population are different than in normal conditions. In this situation, the estimation of the post mortem interval (PMI) is harder because of the lack of information (temperature values), and the lack in the species of forensic interest. In the last century, studies helped to improve knowledge of the fauna associated with buried carrion. In the last period, some workers focused on a few groups of insects (or arthropods) in order to highlight a predictable pattern of their arrival on a corpse, helping to estimate the PMI. Groups are still neglected, because of the little motivation for this topic and the lack of taxonomists. However, study of this specific fauna may provide interesting information for investigation purposes. To better understand the dynamics of insect populations and interpret their processes, it is important to have a better knowledge of the decomposition of corpses when buried. Study of this necrophagous population can give useful information, even if the PMI estimation is less easy to determine. Nevertheless, advances in this particular field of forensic entomology will improve the efficiency of analyses.