Citrus essential oils and four enantiomeric pinenes against Culex pipiens (Diptera: Culicidae)

The aim of this study was to evaluate the toxicity of pinenes (enantiomers of alpha- and beta-) and essential oils from Greek plants of the Rutaceae family against the mosquito larvae of Culex pipiens (Diptera: Culicidae). Essential oils were isolated by hydrodistillation from fruit peel of orange (Citrus sinensis L.), lemon (Citrus limon L.), and bitter orange (Citrus aurantium L.). The chemical composition was determined by gas chromatography/mass spectrometry (GC/MS) analysis. Citrus essential oils contained in high proportion limonene and in lower quantities p-menthane molecules and pinenes. The insecticidal action of these essential oils and enantiomers of their pinenes on mosquito larvae was evaluated. Plant essential oils exhibited strong toxicity against larvae with the LC(50) values ranging from 30.1 (lemon) to 51.5 mg/L (orange) depending on Citrus species and their composition. Finally, the LC(50) value of pinenes ranging from 36.53 to 66.52 mg/L indicated an enantioselective toxicity only for the beta-pinene enantiomer.