Insect Colonisation and the Decomposition Process in Aerated versus Watertight Burial Systems

SIMPLE SUMMARY: Aerated burial systems involve slow air circulation within a mound, caused naturally or artificially. The weak airflow allows bacteria to work in an aerobic environment, accelerating the natural skeletonisation process. The main objective of this study was to document the decomposition level of an animal carcass in an aerated and watertight niche in a special epigean loculus. Pig carcasses (weighing approximately 70 kg each) were used as an experimental model for testing differences between the two systems. Each carcass was removed from the niches at predefined intervals, and the degree of decomposition and the presence of macrofauna were verified. The study examined if insects could colonise carcasses in the two burial systems to determine which fauna were present during the sampling dates. The possible existence of bacterial colonies was also assessed after five years. Our experiments showed that aerated burials facilitate skeletonisation similarly to watertight burial methods. Therefore, aerated burials are a viable alternative to watertight burials in terms of reducing both decomposition time and the costs of urban cemetery planning. It is also an alternative to interment in cemeteries where the soil cannot properly skeletonise. Aerated entombment applies to both hypogeum and epigean solutions. ABSTRACT: In recent years, burial systems have covered increasingly higher costs due to the pollution caused by decomposition products. These products are understood as chemicals and microorganisms in the surrounding soil and groundwater and represent a topical issue. The purpose of this research was to ascertain the extent of decomposition when pig carcasses are buried in two different burial systems (“aerated” vs. “watertight”) and catalogue the arthropods associated with burials at different time-points of removal from niches (after 6, 12, 24, 36, and 60 months). Thirteen taxa were collected in aerated niches, whereas five were collected in watertight niches. The initial access or exclusion of insect colonisers affected overall functional activity. Two Diptera species, Hydrotaea capensis and Megaselia scalaris, were the most abundant, supporting the hypothesis that insects can colonise carcasses in aerated burial systems. Furthermore, some species of bacteria have been documented as facilitators of the initial decomposition process of the carcass. Most bacterial colonies develop only in aerated niches. The trial showed that the first enzymatic–bacterial and insect actions helped promote the process of cadaveric decomposition and later skeletonisation, mainly when associated with aeration modes of the tomb/mound. The results obtained provide essential information on the process of human decomposition and taphonomy in cemeteries. Moreover, these data could benefit forensic science by adding information on insect colonisation and body modification in medico-legal investigations concerning the post-mortem interval in exhumed bodies and illegal burials.