Effect of Some Household Products (Kerosene, Insecticide and Perfume) on Arthropods Colonization on Rats' Cadavers

The most common task of a forensic entomologist is to determine an accurate minimum post-mortem interval (PMI) using necrophagous fly larvae found on carrion. The presence of repellent substances on cadaver is not generally well informed and can be difficult to detect. This study aimed to evaluate the effect of some common household products (kerosene, insecticide, perfume) on arthropods colonization on rats' cadavers including their effect on the type of species, and first insect’s arrival time. As well as relation of the stage of decomposition to both the type of species and first insect’s arrival time. The experiment was performed during spring season. Twenty healthy rat carrions (200 ± 50 g) were randomly divided into four groups; each group was consisted of five rats. Group (1) served as a control, was kept without any substance poured on it. Group 2, Kerosene poured rats, where kerosene was splashed on each rat. Group 3, Insecticide poured rats, where flying insects killer was splashed on each rat. Lastly, 4^th group, Perfume poured rats, where perfume was splashed on each one. The presence of arthropods was checked at regular intervals during the period of experiment. The use of these products didn't only affect the time of first insect's arrival but also type of insects and stage of decomposition. In control group, during the fresh stage of decomposition, the first insects appeared and the most abundant orders were Diptera of families Sarcophagidae, Calliphoridae and Muscidae, followed by Coleoptera (Dermestidae) during the bloat and wet decomposition stages.All presented species were collected from the control group, while Musca domestica and Dermestes frischiididn't appear in any of the poured cadavers (Groups 2, 3, 4) till the end of the experiment. Colonisation delay was for (96.5h ± 0.55) in rats of group (2), (3.5 h ±0.3) in rats of group (3) and (4.5 h ±S.D. 0.4) in rats of group (4). Distinct delay in decomposition stages was observed in kerosene poured rats (Group 2. These results together confirm the repellent effect of some household products on flies and the necessity for forensic entomologists to consider this hypothesis when estimating the PMI.