Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, 31270-901, Belo Horizonte, Minas Gerais, Brazil,
Parasitol Res. 2014 Jan;113(1):417-23. doi: 10.1007/s00436-013-3670-2. Epub 2013 Nov 13.
The tick Rhipicephalus microplus causes significant losses in livestock cattle and has developed increasing resistance to the primary acaricides that are used to treat these infections. The objective of this study was to identify new biomolecules or isolated substances showing acaricidal activity from plants. Larval packet tests were conducted to evaluate the effects of 11 species of plants and three isolated substances (betulinic acid, eugenol, and nerolidol) on R. microplus. An adult female immersion test was performed with the substance that showed the highest larvicidal activity, which was evaluated for inhibition of reproduction. Tests using Licania tomentosa, Hymenaea stigonocarpa, Hymenaea courbaril, Stryphnodendron obovatum, Jacaranda cuspidifolia, Jacaranda ulei, Struthanthus polyrhizus, Chrysobalanus icaco, Vernonia phosphorea, Duguetia furfuracea, and Simarouba versicolor extracts as well as the isolated substance betulinic acid indicated lower acaricidal effects on R. microplus larvae. The extract displaying the best larvicidal activity was the ethanolic extract from L. tomentosa at a concentration of 60%, resulting in a mortality rate of 40.3%. However, nerolidol and eugenol showed larvicidal activity, which was highest for eugenol. Nerolidol caused a 96.5% mortality rate in the R. microplus larvae at a high concentration of 30%, and eugenol caused 100% mortality at a concentration of 0.3%. In the adult immersion test, 5% eugenol was identified as a good biomolecule for controlling R. microplus, as demonstrated by its high acaricidal activity and inhibition of oviposition.
微小牛蜱会给家畜带来巨大损失，并且对用于治疗这些感染的主要杀蜱剂产生了越来越强的耐药性。本研究的目的是从植物中鉴定出具有杀蜱活性的新生物分子或分离物质。进行幼虫包被试验以评估 11 种植物和 3 种分离物质（白桦脂酸、丁香酚和橙花叔醇）对微小牛蜱的影响。对显示出最高杀幼虫活性的物质进行了雌性成虫浸泡试验，评估其对生殖抑制的效果。使用绒毛厚壳桂、石山榕、黄桐、大托叶山榄、蓝花楹、依兰油、四数木、可可树、辣木叶、番石榴和黄桐提取物以及分离物质白桦脂酸进行的试验表明，这些物质对微小牛蜱幼虫的杀蜱效果较低。显示出最佳杀幼虫活性的提取物是浓度为 60%的绒毛厚壳桂乙醇提取物，死亡率为 40.3%。然而，橙花叔醇和丁香酚表现出杀幼虫活性，其中丁香酚的活性最高。橙花叔醇在 30%的高浓度下可导致微小牛蜱幼虫的死亡率达到 96.5%，而丁香酚在 0.3%的浓度下可导致 100%的死亡率。在成虫浸泡试验中，5%的丁香酚被鉴定为控制微小牛蜱的良好生物分子，因为其具有高杀蜱活性和抑制产卵的作用。
