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

[摘要] English: While burial is utilised by criminals as a means of disposing of a body, knowledge of theimpact it has on arthropod succession and decomposition within South Africa is currentlylacking.The study was conducted within a 24 hectare grassland field, located on the University of theFree State grounds. A total of seven pig carcasses (Sus scrofa Linnaeus) were utilised foreach of the two seasonal trials, with six of them being buried in randomly spaced graves atdepths of 60cm and one placed above-ground as a control. Each of the graves was excavatedon predetermined days over each 60 day trial to minimise disturbance and evaluate the impactof differing time periods on decomposition and arthropod succession. After its initialexcavation, grave one was excavated every third day until the conclusion of the trial todetermine the impact of disturbance on buried remains.Decomposition and biomass loss progressed faster on buried carcasses compared to abovegroundduring the winter season. A faster rate of decomposition and biomass loss was seenfor 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, ahigher decomposition and biomass loss rate was recorded on the summer buried carcassescompared to those buried in winter.Dipteran species were seen to dominate on the summer control carcass, while, during thewinter trial, the coleopteran species, Dermestes maculatus De Geer (Dermestidae), was notedto extensively colonise and outcompete present dipteran individuals. With cold, dry climaticconditions leading to the winter control carcass undergoing a form of mummification, adultD. maculatus individuals were seen to congregate on the carcass and reproduce, leading tolarval 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 predatorycoleopteran species and an Acari species. Of those species colonising the winter buriedcarcasses, two Phoridae species were found to be the most abundant, being identified asMegaselia scalaris (Loew) and Conicera tibialis Schmitz, and colonised the buried carcassesfrom 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 speciesfrom the genus Aleochara Gravenhorst (Staphylinidae). Further colonisation of the summerburied carcasses was seen after 30 days, with sarcophagid pupae and the Acari speciesSancassania mycophagus (Mégnin) being sampled from the buried carcasses.From the analyses of data gained from the two seasonal trials, predictions were maderegarding the time frames of decomposition and arthropod succession applicable to buriedcarcasses within central South Africa. Concurrently, alternative methodologies for burialexcavations and entomological evidence collection were suggested for investigators, to takeinto consideration during burial crime scene investigations within central South Africa.

[发布机构] University of the Free State