keywords: Entomotoxicology, Dichlorvos, Clarias gariepinus, Carrion insect, Decomposition
A study was carried out on the forensic entomotoxicological evaluation of carrion insects found on fish poisoned with Sniper (Dichlorvos) on the main campus of the University of Ibadan. Fish (Clarias gariepinus) for the study were obtained from the fish farm on the University Campus. The fish were then euthanized with 5ml of Dichlorvos while the control fish were sacrificed by percussive stunning but without the poison. Adult carrion insects were collected from the fish carrion using a sweep net. The larvae were collected into a bowl by using a scoop, immobilized with hot water and later placed in sample bottles containing 70% ethanol. Pupae were collected using forceps. Carcass temperature was measured using infrared thermometer while relative humidity was recorded with a digital hygrometer. Calliphoridae and Muscidae were the initial pioneers of the decomposing carcass and were seen during the fresh stage, sarcophagidae was seen shortly after the fresh stage of decomposition. The highest mean temperature value for the fish treated with 5ml Dichlorvos was 31.30C while its lowest mean value was 22.60C. It was observed that the temperature on the ninth day was higher than the other days. This is attributed to the heat generated by the active maggots at that stage of decomposition. Dichlorvos was found to retard the growth of carrion larva as shown in Musca domestica larvae when compared with the control. Fast decomposition rate was recorded due to high ambient and carcass temperature. It can be concluded from this study that carrion insects can be used in solving crime puzzles through the extrication of post mortem intervals in conjunction with environmental variables. Since fish carrion in this study attracted a sizable number of carrion insects, it is recommended that fish be used in future forensic case and experimental studies.