Necrophagous arthropods associated with Rat (<i>Rattus norvegicus</i>) Carrion in Abraka, Delta State, Nigeria

Abstract

Carrion is an ecosystem in which different fauna arrive and depart at different times. The arrival time and the growth rate of organisms inhabiting carrion are used to determine circumstances surrounding deaths. Studies on Arthropods associated with Rattus norvegicus carrion have great potential in forensic investigations. The present study was undertaken to determine the abundance of some forensically important arthropods on the carrion of rats buried at different depths namely; 0.6m & 1.21m and on the soil surface in six successions in Abraka, Delta State Nigeria. Entomological analysis was carried out on the carrion by standard procedure. Site climatic factors such as temperature and relative humidity were recorded using a digital thermo-hygrometer. A total of 531 Arthropods consisting of Chrysomya species 61(11.4%), Streblognathus aethiopicus 82(15.4%), Musca domestica 55(10.3%) Necrobia rufipes 35(6.5%) Heteronychus arator 38 (7.1%), Onitis sp. 50(9.4%), Saprinus chalcites 83(15.6%), Bryocharis analis 37(6.9%), Piesocorynus lateralis 25(4.7%), Acropteroxys gracilis 12(2.2%), Trochosa sp.5 (0.9%), Nicrophorus sp. 5(0.9%), Solenopsis sp. 26(4.8%), Cartharsius triconutus 1(0.1%), Margaritus feedatus 6(1.1%) Diaperis sp. 4(0.7%), Olibrus liquidus 4(0.7%), Erytus sp. 1(0.1%) and Julus sp. 1(0.1%) were collected from Rattus norvegicus carrion. The difference in the relative abundance of these necrophagous organisms was statistically significant (F=7.168, p<0.05). More arthropods were collected on the soil surface (51.9%) than 0.61m depth (27.4%) and 1.21m depth (20.5%) and these differences were statistically different (F=2.904, p<0.05). The relative humidity showed a positive correlation with relative abundance (r= 0.49). The organisms collected during the wet months were more in abundance than in the dry months and the difference was statistically significant (t= 0.6736, p<0.05). It is hoped that the data in this study will contribute to post-mortem interval monitoring and forensic investigation in our locality.