Centro de Investigaciones de Plagas e Insecticidas (CONICET-CITEDEF), Juan Bautista de la Salle 4397 (B1603ALO), Villa Martelli, Provincia de Buenos Aires, Argentina.
J Med Entomol. 2012 Mar;49(2):332-5. doi: 10.1603/me11142.
The major components of geranium (Geranium maculatum L.) oil and their mixtures were tested against female Pediculus humanus capitis De Geer (Phthiraptera: Pediculidae). Chemical analysis by gas chromatography coupled to mass spectrometry revealed four major constituents: citronellol (38%), geraniol (16%), citronellyl formate (10.4%), and linalool (6.45%) (concentration expressed as percentage of total). Topical application demonstrated that the most potent component was citronellol and geraniol, with LD50 values 9.7 and 12.7 microg/insect, respectively. Linalool and Citronellyl formate were less toxic with LD50 values 24.7 and 38.5 microg/insect, respectively. Toxicity of these four major constituents in the same proportion as the natural oil, was greater than whole oil and each individual component. Removal of any four constituents produced a decreased in effectiveness. The absence of citronellol caused the greatest decrease in toxicity (DL50 from 2.2 to 10.9 microg/insect), leading us to conclude that this constituent is the major contributor to oil toxicity. The knowledge of the role of each constituent in the toxicity of the whole oil gives the possibility to create artificial blends of different constituents for the development of more effective control agents.
香叶天竺葵（Geranium maculatum L.）油及其混合物的主要成分被测试用于对抗雌性人头虱（Pediculus humanus capitis De Geer）（Phthiraptera：Pediculidae）。气相色谱-质谱联用的化学分析显示出四个主要成分：香茅醇（38％）、香叶醇（16％）、香茅酸甲酯（10.4％）和芳樟醇（6.45％）（浓度以总浓度的百分比表示）。局部应用表明，最有效的成分是香茅醇和香叶醇，LD50 值分别为 9.7 和 12.7 μg/虫。芳樟醇和香茅酸甲酯的毒性较低，LD50 值分别为 24.7 和 38.5 μg/虫。这四个主要成分按天然油中的相同比例混合的毒性大于全油和各个单独成分。去除任何四个成分都会降低效果。缺少香茅醇会导致毒性降低最大（DL50 从 2.2 到 10.9 μg/虫），这使我们得出结论，该成分是油毒性的主要贡献者。了解每个成分在全油毒性中的作用，为开发更有效的控制剂创造不同成分的人工混合物提供了可能性。
