Insect Diversity on Decomposing Domestic Piglets (Sus domesticus ERXLEBEN) Carcasses at Umudike, Southeast Nigeria

Abstract

Outdoor experiments were carried out to identify arthropods colonizing ground-placed and hung piglets (Sus domesticus) carcasses, their species diversity, and decomposition pattern. The trial was carried out in two seasons: July to September, 2019 (wet), and January to March, 2020 (dry) at Michael Okpara University of Agriculture, Umudike Abia State, Nigeria. A total of four healthy piglets with average weight of 3.73 kg were sacrificed for the trial. The piglets died by dislocating their cervical vertebrate (to mimic natural death); two were placed on the ground in metal cage whereas the other two were hung on a tree. Data on carcasses arthropod populations, temperature, weights and decomposition stages and rates were collected. Results showed that the total arthropod taxa of seventeen genera, ten families in four orders were recorded from the carcasses. A total of 29,629 individual insects were counted, belonging mainly to; Calliphoridae, Muscidae, Sarcophagidae, Dermestidae, Staphylinodea, Pyrrhocoridae and Formidae. Their species abundance was; Musca spp. (37.09 %), Chrysomya spp. (12.97 %), Pheidole spp. (12.09), Componotus spp. (9.69 %), Monomorium spp. (6.04 %), respectively. Higher number of insects were collected from ground-placed piglets (34.08%) than hung piglets (28.06%). More insects were recorded during the dry (55.28%) than wet (44.11%) season. Higher insect diversity was also recorded amongst insect species on ground-placed (0.80) than hung (0.72) carcasses. Data also showed that five stages (fresh, bloat, active decay, advanced decay and skeletonization) of decomposition were observed over a duration of 10 days. This study provided base-line data on the local insect fauna associated with the stages of decomposition with emphases on their arrival time, and it is crucial for estimating the post-mortem interval during forensic investigations in south eastern Nigeria.