Toxicity of the essential oil of Illicium difengpi stem bark and its constituent compounds towards two grain storage insects
1Department of Entomology, China Agricultural University, 2 Yuanmingyuan West Road, Haidian District, Beijing
100094, China
2State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875,
China
3Department of Biology, Faculty of Preclinical Medicine, GuangXi Traditional Chinese Medical University, Nanning
530001, China
Abstract
During our screening program for new agrochemicals from Chinese medicinal herbs, the essential oil of Illicium difengpi stem bark was found to possess strong insecticidal activities against the maize weevil, Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) and red flour beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae). A total of 37 components of the essential oil of I. difengpi were identified. The main components of the essential oil were safrole (23.61%), linalool (12.93%), and germacrene D (5.35%). Bioactivities-directed chromatographic separation on repeated silica gel columns led to the isolation of two compounds: safrole and linalool. Safrole showed pronounced contact toxicity against both insect species and (LD50 = 8.54 for S. zeamais; 4.67 μg/adult for T. castaneum) and was more toxic than linalool (LD50 = 24.88 for S. zeamais; 8.12 μg/adult for T. castaneum). The essential oil acting against the two species of insects showed LD50 values of 13.83 and 6.33 μg/adult, respectively. Linalool also possessed strong fumigant toxicity against both insect species (LC50 = 10.02 for S. zeamais; 9.34 mg/L for T. castaneum) and was more toxic than safrole (LD50 = 32.96 and 38.25 mg/L), while the crude essential oil acting against the two species of insects showed LC50 values of 14.62 and 16.22 mg/L, respectively. These results suggest that the essential oil of I. difengpi stem bark and the two compounds may be used in grain storage to combat insect pests.
Keywords: contact toxicity, fumigant, Sitophilus zeamais, Tribolium castaneum
Abbreviations: GC, gas chromatography; MS, mass spectrometry; NMR, nuclear magnetic resonance
Correspondence:
a Chushasha3421@126.com,
b wangchengfang@mail.bnu.edu.cn,
c dushushan@bnu.edu.cn,
d shaoliangliu@126.com,
e zhilongliu@cau.edu.cn, *Corresponding author
Editor: Guy Smagghe was Editor of this paper.
Received: 8 November 2010 | Accepted: 15 August 2011 | Published: 9 November 2011
Copyright: This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.
ISSN: 1536-2442 | Volume 11, Number 152
Chu SS, Wang CF, Du SS, Liu SL, Liu ZL. 2011. Toxicity of the essential oil of Illicium difengpi stem bark and its constituent compounds towards two grain storage insects. Journal of Insect Science 11:152 available online: insectscience.org/11.152
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