Department of Agricultural Biotechnology, College of Agriculture & Life Sciences, Seoul National University, Seoul, South Korea.
Research Institute for Agriculture and Life Sciences, College of Agriculture & Life Sciences, Seoul National University, Seoul, South Korea.
J Med Entomol. 2020 Jul 4;57(4):1149-1156. doi: 10.1093/jme/tjaa014.
Aedes aegypti L. (Diptera: Culicidae) is one of the most medically important mosquito species, due to its ability to spread viruses of yellow fever, dengue fever, and Zika in humans. In this study, the insecticidal activity of 17 plant essential oils was evaluated via topical application against two strains of Ae. aegypti mosquito, Orlando (insecticide-susceptible) and Puerto Rico (pyrethroid-resistant). Initial screens with the Orlando strain showed that cucumber seed oil (2017 sample) was the most toxic, followed by sandalwood and thyme oil. When the essential oils were mixed with permethrin, they failed to show any significant synergism of insecticidal activity. Sandalwood and thyme oils displayed consistently high mortality against the resistant Puerto Rico strain, with low resistance ratios of 2.1 and 1.4, respectively. In contrast, cucumber seed oil showed significantly less activity against Puerto Rico mosquitoes, with a resistance ratio of 45. Bioactivity-guided fractionation of the 2017 sample of cucumber seed oil sample via flash column chromatography produced 11 fractions, and gas-chromatography/mass spectrometry analysis revealed that the three active fractions were contaminated with 0.33, 0.36, and 0.33% of chlorpyrifos-methyl, an organophosphorus insecticide, whereas inactive fractions did not show any trace of it. These results suggested that the insecticidal activity of cucumber seed oil was probably due to the presence of the insecticide, later confirmed with a clean batch of cucumber seed oil obtained in 2018, which showed negligible insecticidal activity. These findings demonstrate clearly the need for essential oil analysis to confirm purity before any claims are made about pesticidal potency.
埃及伊蚊（双翅目：蚊科）是最重要的医学相关蚊种之一，因为它能够在人类中传播黄热病、登革热和寨卡病毒。在这项研究中，通过局部应用评估了 17 种植物精油对两种埃及伊蚊品系（奥兰多（杀虫剂敏感）和波多黎各（拟除虫菊酯抗性））的杀虫活性。对奥兰多品系的初步筛选表明，黄瓜籽油（2017 年样品）毒性最强，其次是檀香油和百里香油。当这些精油与氯菊酯混合时，它们并没有表现出任何显著的杀虫协同作用。檀香油和百里香油对抗性较强的波多黎各品系表现出持续的高死亡率，其抗性比分别为 2.1 和 1.4。相比之下，黄瓜籽油对波多黎各蚊子的活性明显较低，其抗性比为 45。通过快速柱色谱对 2017 年黄瓜籽油样品进行生物活性导向分离，得到 11 个馏分，气相色谱/质谱分析表明，三个活性馏分分别受到 0.33%、0.36%和 0.33%氯吡硫磷-甲基（一种有机磷杀虫剂）的污染，而不活跃的馏分则没有显示出任何痕迹。这些结果表明，黄瓜籽油的杀虫活性可能是由于存在杀虫剂，后来用 2018 年获得的干净黄瓜籽油证实了这一点，这种油几乎没有杀虫活性。这些发现清楚地表明，在声称具有杀农药效之前，有必要对精油进行分析以确认其纯度。
