Fumigant toxicity of Citrus sinensis essential oil on Musca domestica L. adults in the absence and presence of a P450 inhibitor.

Essential oils (EOs) are potential tools for controlling Musca domestica L. In a fumigant assay, M. domestica adults treated with Citrus sinensis EO (LC50=3.9mg/dm(3)), with (4R)(+)-limonene (95.1%) being its main component, died within 15min or less. The terpenes absorbed by the flies and their metabolites, analyzed using SPME fiber, were (4R)(+)-limonene (LC50=6.2mg/dm(3)), α-pinene (LC50=11.5mg/dm(3)), β-pinene (LC50=6.4mg/dm(3)), and two new components, carveol (LC50=1122mg/dm(3)) and carvone (LC50=19mg/dm(3)), in a proportion of 50, 6.2, 12.5, 6.3 and 25%, respectively. Carveol and carvone were formed by oxidation of (4R)(+)-limonene mediated by cytochrome P450, as was suggested by a fumigation assay on flies previously treated with piperonyl butoxide, a P450 inhibitor. In this experiment, an increase in the toxicity of the EO and (4R)(+)-limonene was observed, as well as a lower production of carveol and carvone.
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