INVENTORY OF NECROPHAGOUS INSECTS INVOLVED IN THE DECOMPOSITION PROCESS OF A PIG CORPSE (SUS SCROFA DOMESTICUS L.) EXPOSED TO THE OPEN AIR IN THE SOUTHERN FOREST ZONE OF CÔTE D'IVOIRE

In Côte d'Ivoire, necrophagous insects have since 2008, begun to arouse a keen interest among researchers. After the first works by Adou (2014), on the anthropological aspects, of the colonization of a monkey corpse by insects, others followed between 2015 and 2016. Indeed, Koffi et al. (2017a, 2017b) were able to demonstrate, using openair pig carcasses, a well-defined process of corpse colonization by necrophagous insects, and the contribution of these last to cadaverous weight loss. But the identification of these insects stopped at the taxonomic level of the family. This is the reason why the purpose of this work was to make a specific inventory of the necrophagous insects involved in the decomposition process of an open-air pig carcass in the southern forest zone of Côte d'Ivoire. To do this, 3 series of experiments were carried out on 3 ecologically identical sites in the city of Abidjan, between August 19, 2015 and September 22, 2016. Trapping devices, adapted to various groups of insects, and using whole corpses of pig as bait, have been set up on the CNRA (Centre National de Recherche Agronomique / National Center for Agricultural Research), ZOO and CNF (Centre National de Floristique/ National Floristic Center) sites. At the end of the work carried out, the species harvested and identified were divided into the 2 main orders of Diptera and Coleoptera. Fifteen species of Diptera were grouped into 5 families: Calliphoridae, Sarcophagidae, Muscidae, Piophilidae and Stratiomyidae. Among the Calliphoridae whose species are used for post mortem dating, the most abundant was Chrysomya albiceps with a rate varying between 7.45 and 13.38% of the average size. The Coleoptera were represented by 6 families, namely Cleridae, Histeridae, Dermestidae, Tenebrionidae, Trogiidae and Scarabaeidae. Necrobia rufipes, which belongs to the family Cleridae, was the most abundant species with a rate ranging from 55.89 to 59.99% of the average number of Coleoptera species harvested. Analysis of the ecological index of biodiversity showed a higher Richness, Shannon’s Index and Equitability in "fresh cadaver" (H '= 1.73 E = 0.83) and "swelling/active decomposition" stages (H = 2.37 E = 0.82). The high values of the Richness and Shannon’s Index for these stages of decomposition, have reflected the cohabitation of many species present in small numbers. In addition, the high values of Equitability in "fresh cadaver" and "swelling/active decomposition" stages have shown a fair distribution of species within the corpse ecosystem. Finally, in the framework of an entomological expertise to date deaths, this inventory work of the necrophagous entomological fauna, made it possible to highlight, the effective presence, throughout the year, species of Diptera of the family Calliphoridae, which are mainly used for the estimation of a short post mortem interval, since these last are the first to colonize a cadaver exposed to the open air in the southern forest area of Côte d’Ivoire (Koffi et al., 2017a).