The influence of clothing, wrapping and physical trauma on carcass decomposition and arthropod succession in central South Africa

[摘要] English: Forensic entomology is the study of arthropods associated with bodies. Arthropod successional studies have been successfully used to estimate a postmortem interval. This research was to determine the influence of a) seasons, b) clothing, c) wrapping and d) knife wounds on carcass decomposition and arthropod succession. The experimental site consisted of a 26 hectares grass field interspersed with trees. For the wrapped trials, six pig (Sus scrofa) carcasses were divided into three sample groups, each with a clothed carcass and an unclothed carcass wrapped in sheeting. Arthropod sampling was done (i) daily, (ii) five day intervals and (iii) ten day intervals. Two additional unwrapped carcasses, one with clothes and one without, were sampled daily as controls. For the wounds trials six carcasses were divided into three groups. Each group consisted of a carcass with clothes and one without clothes. The wounds consisted of (i) a knife wound to the throat, (ii) three deep knife wounds, in the back, in the front thoracic and in the front abdominal region. The controls, were without any wounds. Oviposition occurred simultaneously and was not delayed or hastened by the presence of wrapping, clothing or wounds. However, during the winter wrapped trials there was a delay of four days. In winter, the carcasses remained acceptable to Diptera for oviposition over an extended period. Oviposition continued up to two months after placement, whilst in the warmer seasons oviposition occurred within the first few days. The Diptera did not select the wounds as oviposition sites. Calliphoridae and Sacrophagidae were the dominant Diptera recorded during all the trials. In the autumn and summer seasons Chrysomya marginalis and Chrysomya albiceps were the dominant species. In the spring seasons, the dominant species were Chrysomya chloropyga and C. albiceps. In the winter seasons, Sarcophaga cruentata , C. chloropyga, Calliphora vicina, and Lucilia spp. were the species breeding on the carcasses. Muscidae adults were present during all the seasons, but no maggots of this family were recorded. Due to the short oviposition time during warmer seasons, the maggots were of a similar age at any time. Due to the extended oviposition that occurred during winter, different instar groups, often the same species, were present at any time. In all seasons the Coleoptera community present on the carcasses were dominated by Dermestes maculatus (adults and larvae) and Necrobia rufipes. In the summer Thanatophilus micans (adults and larvae) and Histeridae spp. were also recorded on the carcasses. There was no overall difference in arthropod succession between any of the carcasses. During the autumn seasons, noticeable predation by C. albiceps maggots on C. marginalis maggots was observed. There was limited maggot predation during the spring trials and some predation observed during the summer trials. Presence of clothing, wrapping and wounds had no influence the Coleoptera community. In the winter seasons, D. maculatus larvae were found while the maggots were still present on the carcasses. In summer seasons, they were only present after maggot migration. Significant maggot mortality was associated with the wrapped carcasses during the warmer seasons. The presence of the sheets or clothing did allow the maggots to move more freely on the surface of the carcasses, especially in the summer. Less skin remained on the wrapped or clothed carcasses after the maggots migrated to pupate.

[发布机构] University of the Free State