Chemical composition of the essential oils isolated from peel of three citrus species and their mosquitocidal activity against Culex pipiens.

Three essential oils (EOs) were isolated from the peel of citrus fruits Citrus reticulata L., Citrus reticulata chinase Blanco and Citrus sinensis (L.) Osbeck (Family: Rutaceae) and evaluated against Culex pipiens L.1758 (Family: Culicidae). Chemical composition indicated that the EOs were rich in essential phytochemicals including hydrocarbons, monoterpenes and sesquiterpenes. These constituents revealed some variability among the oils displaying interesting chemotypes limonene (35-51%), 1R-α-pinene (1.04-2.5%), γ-terpinene (0.46-5.65%) and sabinene (0.51-5.42%). The toxicity proved that C. sinensis oil had more effect than C. reticulata chinase and C. reticulata oils against larvae (LC50 = 15.35, 16.11 and 32.84 mg/L, respectively). However, C. reticulate was the most active as fumigant against adults (LC50 2.74 μL/L air). The in vivo effect on acetylcholine esterase (AChE), carboxyl esterase (CbE), acid phosphatase (ACP), alkaline phosphatase (ALP), adenosine triphosphatase (ATPase) and glutathione-S-transferase (GST) were also demonstrated. To the best of our knowledge, this is the first report about the chemical composition and mosquitocidal activity of C. reticulata chinase essential oils. Conclusively, the tested essential oils could be used as eco-friendly alternatives in mosquitoes control programme.