%0 Journal Article
%T Toxicity of Rhododendron anthopogonoides Essential Oil and Its Constituent Compounds towards Sitophilus zeamais
%A Kai Yang
%A Yu Xin Zhou
%A Cheng Fang Wang
%A Shu Shan Du
%A Zhi Wei Deng
%A Qi Zhi Liu
%A Zhi Long Liu
%J Molecules
%D 2011
%I MDPI AG
%R 10.3390/molecules16097320
%X The screening of several Chinese medicinal plants for insecticidal principles showed that essential oil of Rhododendron anthopogonoides flowering aerial parts possessed significant toxicity against maize weevils, Sitophilus zeamais. A total of 37 components were identified in the essential oil and the main constituents of the essential oil were 4-phenyl-2-butanone (27.22%), nerolidol (8.08%), 1,4-cineole (7.85%), caryophyllene (7.63%) and ¦Ã-elemene (6.10%), followed by ¦Á-farnesene (4.40%) and spathulenol (4.19%). Repeated bioactivity-directed chromatographic separation on silica gel columns led us to isolate three compounds, namely 4-phenyl-2-butanone, 1,4-cineole, and nerolidol. 4-Phenyl-2-butanone shows pronounced contact toxicity against S. zeamais (LD50 = 6.98 mg/adult) and was more toxic than either 1,4-cineole or nerolidol (LD50 = 50.86 mg/adult and 29.30 mg/adult, respectively) against the maize weevils, while the crude essential oil had a LD50 value of 11.67 mg/adult. 4-Phenyl-2-butanone and 1,4-cineole also possessed strong fumigant toxicity against the adults of S. zeamais (LC50 = 3.80 mg/L and 21.43 mg/L) while the crude essential oil had a LC50 value of 9.66 mg/L.
%K Rhododendron anthopogonoides
%K Sitophilus zeamais
%K contact toxicity
%K fumigant
%K 4-phenyl-2-butanone
%K essential oil composition
%U http://www.mdpi.com/1420-3049/16/9/7320