Repellent effect of some household products on fly attraction to 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. More often, blowflies (Diptera: Calliphoridae) are the first insects to detect the cadaver and, if the circumstances are favourable, to leave eggs on the body. However, several studies reveal that products such as gas or paint found on the cadaver induce a delay in the colonisation of the body, leading to an under-estimate of the PMI. Six common household products (gas, mosquito citronella repellent, perfume, bleach, hydrochloric acid and soda) were added to dead rats (Rattus norvegicus) in a field (Lille Forensic Institute, France). The presence of necrophagous flies was checked at regular intervals during 1 month. This experiment was repeated at the same period for four consecutive years. Results clearly showed the repellent effect of three of the six tested substances: gas (petroleum spirit), perfume and mosquito citronella repellent, which resulted in a mean delay of several days in the appearance of the first Dipteran species. Experiments were then carried out in controlled conditions in order to confirm previous observations. An olfactometer was specially designed to observe the behaviour of female Calliphora vicina (Diptera: Calliphoridae) in response to mice (Mus musculus) cadaver odour stimuli combined with household products. Dead mouse odour was a strong attractive stimulus for most of the tested individuals. Furthermore, it was noticed that the presence of mosquito citronella repellent, perfume, hydrochloric acid and paradichlorobenzene produced a significant repellent effect on female flies. All 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.
Institut de Médecine Légale et Sociale, Faculté de Médecine, Place de Verdun, 59045 Lille Cedex, France. damien@forenseek.org
Damien
D
Charabidze
Benoit
B
Bourel
Valery
V
Hedouin
Didier
D
Gosset
D000393:Air Pollutants; D000818:Animals; D002253:Carbonated Beverages; D002722:Chlorobenzenes; D031743:Cymbopogon; D004175:Diptera; D004202:Disinfectants; D004772:Entomology; D005247:Feeding Behavior; D005260:Female; D018732:Forensic Anthropology; D049429:Forensic Pathology; D005742:Gasoline; D006801:Humans; D006851:Hydrochloric Acid; D007302:Insect Repellents; D007306:Insecticides; D051379:Mice; D009812:Odorants; D010476:Perfume; D011180:Postmortem Changes; D051381:Rats; D012973:Sodium Hypochlorite
D000393:Air Pollutants; D002722:Chlorobenzenes; D004202:Disinfectants; D005742:Gasoline; D007302:Insect Repellents; D007306:Insecticides; D010476:Perfume; C018511:4-dichlorobenzene; D012973:Sodium Hypochlorite; D006851:Hydrochloric Acid