Checklist of Insects on Asphyxiated Carrion and Their Forensic Importance in Southern Nigeria

Insects associated with vertebrate carrions play an important role in forensic investigations, especially in estimating post-mortem interval (PMI). Unfortunately, baseline data on local insect species associated with carrions in southern Nigeria is still limited. In this study, a checklist was compiled of insects associated with asphyxiated pig carrion was carried out in a grassland habitat. The study was conducted across both dry and rainy seasons of 2023, 2024, and 2025. Fresh pig carrions of 21kg were humanely euthanized by asphyxiation and exposed in wire-mesh cages to exclude vertebrate scavengers but allowed insects access. Insect sampling on the carrions was carried out throughout the decomposition stages. Adult and immature insects were collected, preserved, and identified to species using standard morphological keys. Four stages of carrion decomposition were observed for both seasons, but tissue depletion was faster during the rainy season than the dry season. Insect species collected on the carrions were 25 in 19 families, and 6 orders. The dipterans were the earliest and most dominant colonizers, starting from the fresh to wet stages. The coleopterans became prominent during dry stages throughout the skeletonized remains. Seasonal and interannual variations in species composition were also observed across the three-year study period. The findings provide a comprehensive checklist of carrion-associated insects in a grassland habitat in southern Nigeria and contribute baseline data for forensic entomology in the region. This study emphasizes the importance of localized entomological data for improving the accuracy of PMI estimation and forensic investigations in tropical environments.