Programa de Pós-Graduação em Biodiversidade e Conservação da Natureza, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Minas Gerais, Brazil.
Programa de Pós-Graduação em Ciências Animal, Universidade Federal de Goiás, Goiás, Brazil.
Vet Parasitol. 2021 Dec;300:109606. doi: 10.1016/j.vetpar.2021.109606. Epub 2021 Oct 21.
The use of natural products in research on tick control for Rhipicephalus microplus is increasing year by year, with promising results. In this regard, the aim of the present study was to phytochemically characterize the essential oils (EOs) of Leptospermum scoparium, Origanum vulgare and Litsea cubeba, and to evaluate the acaricidal activity of these EOs in solutions prepared using ethanol, dimethylsulfoxide (DMSO) and Tween 80 on larvae and females of R. microplus. In addition, three L. scoparium fractions were also isolated and their acaricidal activity on these larvae and adult females was tested. Gas chromatography and mass spectrometry results showed that cis-calamenene (29.82 %), carvacrol (64.85 %) and geranial (42.44 %) were the majority compounds of L. scoparium, O. vulgare and L. cubeba, respectively. Three fractions were isolated from L. scoparium: A1, rich in sesquiterpene hydrocarbons, and A2 and A3, rich in β-triketones. Bioassays on unfed larvae (immersion test) were performed using all the EOs at concentrations from 2.5 to 10.0 mg/mL; and using the three fractions obtained from L. scoparium EO at concentrations from 0.625 to 10 mg/mL. We observed 100 % mortality of larvae in all treatments with L. scoparium EO at all concentrations (diluted both in DMSO and in ethanol), and in treatments with O. vulgare EO diluted in DMSO. However, L. cubeba EO only gave rise to more than 99 % mortality at a concentration of 10 mg/mL, using the same solvents. For engorged females, the immersion test was performed at concentrations from 2.5 to 10.0 mg/mL. Percentage control greater than 90 % was observed only at the highest concentrations of L. scoparium and O. vulgare EOs diluted in DMSO and ethanol, while L. cubeba EO did not reach 90 % control in any of the treatments. In tests on L. scoparium fractions, larval mortality in the fractions rich in β-triketones (A2 and A3) was above 97 % at a concentration of 2.5 mg/mL, while in the A1 fraction, rich in sesquiterpene hydrocarbons, at the same concentration (2.5 mg/mL), mortality did not reach 22 %. In the adult immersion test, the percentage control was higher than 98 % at the lowest concentration (2.5 mg/mL) of the A1 fraction, while in the treatments with the fractions A2 and A3, the control levels were 16 and 50 %, respectively. Thus, we can conclude that the EOs of L. scoparium, O. vulgare and L. cubeba have acaricidal activity on R. microplus, as also do the fractions derived from L. scoparium EO.
天然产物在蜱控制研究中的应用逐年增加，前景广阔。有鉴于此，本研究的目的是对 Leptospermum scoparium、Origanum vulgare 和 Litsea cubeba 的精油（EOs）进行植物化学表征，并评估这些 EOs 在使用乙醇、二甲基亚砜（DMSO）和吐温 80 制备的溶液中对 Rhipicephalus microplus 幼虫和雌性的杀蜱活性。此外，还分离了三种 Leptospermum scoparium 馏分，并测试了它们对这些幼虫和成年雌性的杀蜱活性。气相色谱和质谱结果表明，顺式-金合欢烯（29.82%）、香芹酚（64.85%）和柠檬醛（42.44%）分别是 L. scoparium、O. vulgare 和 L. cubeba 的主要化合物。从 L. scoparium 中分离出三种馏分：A1，富含倍半萜烃，A2 和 A3，富含β-三酮。在未进食的幼虫（浸泡试验）中，使用所有 EOs 在 2.5 至 10.0 mg/mL 浓度下进行生物测定；并使用从 L. scoparium EO 获得的三种馏分在 0.625 至 10 mg/mL 浓度下进行生物测定。我们观察到，在所有使用 L. scoparium EO 进行的处理中，幼虫在所有浓度（在 DMSO 和乙醇中稀释）下均达到 100%的死亡率，在使用 DMSO 稀释的 O. vulgare EO 的处理中也是如此。然而，只有在使用相同溶剂的 10 mg/mL 浓度下，L. cubeba EO 才能达到超过 99%的死亡率。对于饱血的雌性，在 2.5 至 10.0 mg/mL 浓度下进行浸泡试验。只有在 DMSO 和乙醇中稀释的 L. scoparium 和 O. vulgare EOs 的最高浓度下观察到大于 90%的控制率，而 L. cubeba EO 在任何处理中均未达到 90%的控制率。在 L. scoparium 馏分的试验中，在 2.5 mg/mL 浓度下，富含β-三酮的馏分（A2 和 A3）对幼虫的死亡率高于 97%，而在富含倍半萜烃的 A1 馏分中，相同浓度（2.5 mg/mL）下的死亡率未达到 22%。在成虫浸泡试验中，在 A1 馏分的最低浓度（2.5 mg/mL）下，控制率高于 98%，而在馏分 A2 和 A3 的处理中，控制率分别为 16%和 50%。因此，我们可以得出结论，L. scoparium、O. vulgare 和 L. cubeba 的 EOs 对 R. microplus 具有杀蜱活性，L. scoparium EO 衍生的馏分也是如此。
