Decomposition and insect succession on cadavers inside a vehicle environment
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This study presents differences in rate of decomposition and insect succession between exposed carcasses on the soil surface and those enclosed within a vehicle following carbon monoxide (CO) poisoning. Nine 45-kg pigs were used as models for human decomposition. Six animals were sacrificed by CO gas, half of which were placed within the driver’s side of separate enclosed vehicles and half were placed under scavenger-proof cages on the soil surface. A further three animals were sacrificed by captive headbolt and placed under scavenger proof cages on the soil surface. The pattern of insect succession and rate of decomposition were similar between surface carcasses within trials regardless of the mode of death. Progression through the physical stages of decomposition was 3–4 days faster in the enclosed vehicle due to higher temperatures there compared to external ambient temperatures. Patterns of insect succession also differed between the vehicle and surface treatments. Carcass attendance by representatives of the Calliphoridae was delayed within the vehicle environment by 16–18 h, while oviposition was not observed until 24–28 h following death. In contrast, attendance by Calliphoridae at surface carcasses occurred within 1 h of death, and oviposition occurred within 6–8 h of death. Typical patterns of insect succession on the carcasses were also altered. Carcass attendance by representatives of the Coleoptera occurred during the bloat stage of decomposition at surface carcasses but was delayed until the onset of wet decomposition (as defined by carcass deflation and breakage of the skin) within the vehicle environment. This study provides baseline data outlining the decomposition patterns of a carcass enclosed within a vehicle following CO poisoning in Western Australia. Understanding how variations in decomposition situations impact on the rate of decomposition and patterns of insect succession is essential to obtaining an accurate estimate of minimum post-mortem interval (PMI).
KeywordsCarbon monoxide poisoning Decomposition Forensic entomology Insect Suicide Vehicle
We would like to thank Andy Szito, Department of Entomology, Agriculture Western Australia, for species determination, Natalie Campman, Jeremy Lindsey and Dr. Michelle Harvey for their assistance with sampling and rearing of entomological samples. For helpful comments on earlier versions of this manuscript, we thank Dr. Alexander Larcombe, Clinical Sciences, Telethon Institute for Child Health Research, Western Australia. Thanks are also extended to the Western Australian Police Property Tracing Section who provided the vehicles used in this study. Special thanks to Bob Cooper (University of Western Australia) for granting access to the study site and ongoing field support. This research was conducted with the approval of the University of Western Australia Animal Experimentation Ethics Committee (Ethics no. RA/3/100/022).
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