Effect of seasons on the decomposition by necrophagous insects of pig (Sus scrofa domesticus L.) carcasses exposed to the open air in the Sudano-guinean and Sub-sudanese zones of Côte d'Ivoire

Abstract

Determining the post-mortem interval (PMI) of a corpse discovered 72 hours after death is becoming complex and imprecise in forensic medicine. It is necessary to use other investigative methods to determine the date of death. The aim of this research was to determine the impact of the seasons on the decomposition of pig corpses exposed to the open air by necrophagous insects. The research was carried out in the North (at the Botanical Garden of the Peleforo Gon Coulibaly University in Korhogo) and in the Centre (in the Bouaké region). Insects were collected directly from decomposing carcasses using a mowing net and flexible forceps for larvae and Coleoptera. Pitfall-traps were also used for collection. Diptera and Coleoptera were collected during the dry and rainy seasons in the Sudano-guinean and Sub-Sudanese zones. Chrysomya albiceps, belonging to the Calliphoridae, was the majority species. Because of its plethora of species in the two study areas, C. albiceps could be one of the main species for determining the minimum MPI in Côte d'Ivoire. Five stages of decomposition were observed in the two study zones, although a sixth stage (dry putrefaction) was observed in the Sub-sudanese zone during the harmattan period. Stratiomyidae and Piophilidae contributed to the total decomposition of carcasses during the rainy season. The Histeridae family was the richest in species. Dermestes maculatus was the richest in individuals. Carcasses in the rainy and dry seasons were respectively decomposed by an average of 97.18% in the rainy season and 84.32% in the dry season in the two study areas.