Impact of Marabunta ants on post-mortem interval estimation in pigs: Insights from Okuku, Nigeria

Abstract

The rising homicide rates in Nigeria underscore the necessity for comprehensive post-mortem interval (PMI) estimations to enhance the reliability of forensic investigations. This study investigates the impact of Marabunta ants (Hymenoptera: Formicidae) on the decomposition process and PMI estimation in pig carcasses during the wet season in Okuku, Nigeria. Using two juvenile domestic pigs, we employed a controlled experimental approach at the Department of Anatomy and Forensic Anthropology Research Facility. The study spanned 30 days, with systematic observations of postmortem changes, insect activity and environmental conditions recorded at specified intervals. Results indicated pronounced effects of Marabunta ants on decomposition dynamics. Notably, the presence of these ants altered the expected insect succession patterns, delaying the colonisation by blowflies, which typically dominate the initial decay stages. By the second day, marked ant activity was observed, leading to distinct bite marks on the carcasses, while the other carcasses exhibited standard decomposition without any interference. Accumulated degree days (ADD) and total body scores (TBS) demonstrated a parabolic relationship, revealing rapid initial decay followed by a stabilisation phase as skeletonisation progressed. This research confirms that environmental conditions and insect activities significantly influence decomposition rates and PMI estimations. The findings suggest a need for forensic practitioners to recognise the role of Marabunta ants in decay processes and the potential misinterpretations of ant-induced marks as perimortem injuries. Future studies should explore seasonal variations in decomposition and insect succession to refine forensic entomological methodologies.