[Bioactivity and chemical composition of essential oil from Zanthoxylum beecheyanum var. alatum leaves against Culex pipens quinquefasciatus (Diptera: Culicidae)].

The repellent activity of steam-distilled essential oil from Zanthoxlum beecheyamum var. alatum fresh leaves against Culex pipens quinquefasciatus was evaluated according to the "Laboratory Efficacy Criterions of Public Health Insecticides for Pesticide Registration-Repellent (GB/T 17322. 10-1998)" with some modifications in test procedure, the fumigating insecticidal activity of the essential oil to Cx. pipens quinquefasciatus adults was assessed by the "Efficacy Test Methods of Public Health Insecticides for Pesticide Registration-Method of Laboratory Efficacy Test for Electric Mat (GB 13917.5-1992)", and the larvicidal and pupicidal activities of the essential oil against Cx. pipens quinquefasciatus were investigated by immersion method in laboratory. Besides, the chemical components of the essential oil were analyzed and determined by gas chromatography-mass spectrometry. At the dosage of 1.5 mg x cm(-2), the essential oil provided 100% protection against laboratory-reared female blood-starved individuals of Cx. pipens quinquefasciatus for (6.54 +/- 0.17) h. The 24 h LC50 value of the essential oil for Cx. pipens quinquefasciatus adults was 6.895 microg x cm(-3) when the fumigating dosage was 11.850 microg x cm(-3), and the KT50 value of the essential oil for the adults was 6.46 min. The 24 h LC50 value of the essential oil for IV instar larvae was 119.020 microg x ml(-1). Seventeen compounds in the essential oil were identified, accounting for 97.4% of the total. This essential oil exhibited high repellent activity and remarkable toxicity against Cx. pipens quinquefasciatus.