Experimental study of coumatetralyl (anti-coagulant poison) accumulation in Lucilia sericata (Diptera: Calliphoridae)

P. Magni; A. Natale; P. Capra; C. Abete; M. Vincenti

In addition to their well-known use in the estimation of postmortem interval (PMI) insects that feed on carcasses may also represent a reliable specimen for toxicological analyses especially in the absence of tissues and fluids normally taken for such purpose. Many researchers have demonstrated the extraction of drugs and chemicals (e.g. morphine, cocaine, opiates, benzodiazepines, paracetamol, mercury) from insect larvae associated with a corpse. However, little research has focused on the analyses of poison detection in insect larvae such as organophosphates. Moreover, it is well demonstrated that accumulation of such compounds can modify the grow rate of necrophagous insects and as a consequence the determination of PMI could be compromised. Cumarine compounds have anti-coagulant properties and they are used in anti-coagulant therapies. Coumatetralyl is a product used for eradicating vermin such as rats. Its mode of action is that it blocks the formation of prothrombin, inhibits blood coagulation and causes death by internal haemorrhaging. It is very cheap and easy to purchase. Samples extracted from poisoned cats and dogs and analysed by the toxicological centre (ISZ) have shown that cumarine compounds are one of the most used chemicals (single or mixed with something else) for poisoned baits in Piedmont Region (North West of Italy). The aim of this research was the identification and quantification of the presence and concentration of Coumatetralyl in immature an mature stages of blowfly larvae. Moreover, it was observed how the grow rates of blowfly larvae can be modified by the presence of this compound in the substrate. Following egg hatch blowfly larvae were reared on cow liver mixed with different concentration of Coumatetraryl from 0, 5, 50, 500 ppb. Toxicological analyses were performed using LC/MS-MS techniques on L. sericata II instar, III instar, pupa, puparium and adults. Results obtained demonstrate that L. sericata accumulates Coumatetraryl differently throughout its life history and that the concentration of the substance varies in the pabulum. The rate of metabolism and elimination of this substance will be discussed and its effect on the growth and survival rate on the different life history stages of L. sericata.

Experimental study of coumatetralyl (anti-coagulant poison) accumulation in Lucilia sericata (Diptera: Calliphoridae)

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