title: Identification of Larvicidal Constituents of the  Essential Oil of Echinops grijsii Roots against the  Three Species of Mosquitoes.
abstract: The screening of Chinese medicinal herbs for insecticidal principles showed that the essential oil of Echinops grijsii Hance roots possessed significant larvicidal activity against mosquitoes. The essential oil was extracted via hydrodistillation and its constituents were determined by gas chromatography-mass spectrometry (GC-MS) analysis. GC-MS analyses revealed the presence of 31 components, with 5-(3-buten-1-yn-1-yl)-2,2'-bithiophene (5-BBT, 27.63%), αterthienyl (α-T, 14.95%),1,8-cineole (5.56%) and cis-β-ocimene (5.01%) being the four major constituents. Based bioactivity-directed chromatographic separation of the essential oil led to the isolation of 5-BBT, 5-(4-isovaleroyloxybut-1-ynyl)-2,2'-bithiophene (5-IBT) and αT as active compounds. The essential oil of E. grijsii exhibited larvicidal activity against the fourth instar larvae of Aedes albopictus, Anopheles sinensis and Culex pipiens pallens with LC50 values of 2.65 μg/mL, 3.43 μg/mL and 1.47 μg/mL, respectively. The isolated thiophenes, 5-BBT and 5-IBT, possessed strong larvicidal activity against the fourth instar larvae of Ae. albopictus(LC50 = 0.34 μg/mL and 0.45 μg/mL, respectively) and An. sinensis(LC50 = 1.36 μg/mL and 5.36 μg/mL, respectively). The two isolated thiophenes also had LC50 values against the fourth instar larvae of C. pipiens pallens of 0.12 μg/mL and 0.33 μg/mL, respectively. The findings indicated that the essential oil of E. grijsii roots and the isolated thiophenes have an excellent potential for use in the control of Ae.albopictus, An. sinensis and C. pipiens pallens larvae and could be used in the search for new, safer and more effective natural compounds as larvicides.
authors.affiliation: Department of Entomology, China Agricultural University, Haidian District, Beijing 100193, China. zhaomeiping@ioz.ac.cn.
authors.forename: Mei Ping
authors.initials: MP
authors.lastname: Zhao
authors.affiliation: Department of Entomology, China Agricultural University, Haidian District, Beijing 100193, China. lqzwyz@cau.edu.cn.
authors.forename: Qi Zhi
authors.initials: QZ
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Infectious Disease Prevention and Control, Collaborative Innovation Center of Diagnosis and Treatment of Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China. liuqiyong@icdc.cn.
authors.forename: Qiyong
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Entomology, China Agricultural University, Haidian District, Beijing 100193, China. zhilongliu@cau.edu.cn.
authors.forename: Zhi Long
authors.initials: ZL
authors.lastname: Liu
mesh_terms: D000818:Animals; D009033:Culicidae / Q000187:drug effects*; D031182:Echinops Plant / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D007306:Insecticides / Q000737:chemistry* / Q000494:pharmacology*; D009682:Magnetic Resonance Spectroscopy; D009822:Oils, Volatile / Q000737:chemistry* / Q000494:pharmacology*; D021261:Parasitic Sensitivity Tests; D064209:Phytochemicals / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry*
chemical_list: D007306:Insecticides; D009822:Oils, Volatile; D064209:Phytochemicals
keywords: Echinops grijsii; larvicidal  activity;  Aedes albopictus;  Anopheles sinensis;  Culex pipiens pallens