Decomposition and arthropod succession on buried remains during winter and summer in central South Africa: forensic implications and predictive analyses

English: While burial is utilised by criminals as a means of disposing of a body, knowledge of the impact it has on arthropod succession and decomposition within South Africa is currently lacking. The study was conducted within a 24 hectare grassland field, located on the University of the Free State grounds. A total of seven pig carcasses (Sus scrofa Linnaeus) were utilised for each of the two seasonal trials, with six of them being buried in randomly spaced graves at depths of 60cm and one placed above-ground as a control. Each of the graves was excavated on predetermined days over each 60 day trial to minimise disturbance and evaluate the impact of differing time periods on decomposition and arthropod succession. After its initial excavation, grave one was excavated every third day until the conclusion of the trial to determine the impact of disturbance on buried remains. Decomposition and biomass loss progressed faster on buried carcasses compared to aboveground during the winter season. A faster rate of decomposition and biomass loss was seen for the above-ground carcass versus the below-ground carcass during the summer season, mainly due to heavy rainfall causing waterlogging of the graves. Between the two seasons, a higher decomposition and biomass loss rate was recorded on the summer buried carcasses compared to those buried in winter. Dipteran species were seen to dominate on the summer control carcass, while, during the winter trial, the coleopteran species, Dermestes maculatus De Geer (Dermestidae), was noted to extensively colonise and outcompete present dipteran individuals. With cold, dry climatic conditions leading to the winter control carcass undergoing a form of mummification, adult D. maculatus individuals were seen to congregate on the carcass and reproduce, leading to larval aggregation during the active decay stage. During the trials, only dipteran species were found to colonise the winter buried carcasses, whereas the summer buried carcasses were colonised by two dipteran species, a predatory coleopteran species and an Acari species. Of those species colonising the winter buried carcasses, two Phoridae species were found to be the most abundant, being identified as Megaselia scalaris (Loew) and Conicera tibialis Schmitz, and colonised the buried carcasses from day 21 onwards. Later occurring dipteran species in winter included Muscina stabulans (Fallén) and a species of the genus Leptocera Olivier. Summer buried carcasses saw initial colonisation occurring from day 21 by phorid M. scalaris and a coleopteran beetle species from the genus Aleochara Gravenhorst (Staphylinidae). Further colonisation of the summer buried carcasses was seen after 30 days, with sarcophagid pupae and the Acari species Sancassania mycophagus (Mégnin) being sampled from the buried carcasses. From the analyses of data gained from the two seasonal trials, predictions were made regarding the time frames of decomposition and arthropod succession applicable to buried carcasses within central South Africa. Concurrently, alternative methodologies for burial excavations and entomological evidence collection were suggested for investigators, to take into consideration during burial crime scene investigations within central South Africa.