Succession pattern of insects in relation to killing methods of Rattus norvegicus at Delta State University, Abraka, Nigeria

Abstract

The succession pattern of insects associated with the strangling and slaughtering of rat (Rattus norvegicus) was conducted between March and June 2017. Four (4) Albino Wistar rats were killed using strangle and slaughter methods, one method for a pair. The rat carcasses were secured from scavengers and restricted from human interference in a way that did not necessarily restrict access to the carcasses and also enabled insect collection. Insects were collected daily by hand picking and with the aid of aerial net, forceps and fine paintbrush. Collection was done within short period while checking the physical condition of carcass to note the stages of decay. Six insect families of three orders were collected from the carcass killed by strangling namely the Muscidae (32%), Sarcophagidae (16%), Calliphoridae (16%), Dermestidae (16%), Chrysomelidae (4%) and Cleridae (5%). In the carcass killed by slaughtering method, the families obtained were Muscidae (50%), Sarcophagidae (18%) Calliphoridae (18%), Dermestidae (9%), Staphylindae (5%). There was no significant difference (P>0.05) in the succession pattern of the insects though more individuals were obtained in the strangled carcass (55%) compared to the slaughtered carcass (45%). This study shows the succession pattern may have no significant or obvious influence on the decomposition of carcasses. Therefore there is need to probe further into other killing methods.

Keywords: Carcass; decomposition; forensic; strangled; slaughtered