Assessment of different Lippia sidoides genotypes regarding their acaricidal activity against Rhipicephalus (Boophilus) microplus

Abstract The aim of this study was to select different genotypes of Lippia sidoides with the highest activity against larvae and engorged females of the tick Rhipicephalus (Boophilus) microplus. The germplasms studied were LSID006, LSID102, LSID103 and LSID104. The LSID104 genotype, that presented carvacrol as a major constituent, was the germplasm with the worst larvicide effect (LC50 2.99 mg/mL). The LSID006 genotype was the least effective against engorged females (LC50 12.46 mg/mL), and it was chemically similar to the LSID102 genotype, which presented the highest acaricide activity (LC50 2.81 mg/mL). We conclude that chemical similarity of the germplasms was not correlated with acaricide activity against R. (B.) microplus. The essential oil of L. sidoides is a potent natural agent. However, the findings of this work provide a better understanding for product development based on this natural product, which must consider synergic effects or the action of minor compounds.

摘要 本研究旨在筛选出对微小牛蜱（Rhipicephalus (Boophilus) microplus）幼虫及饱血雌蜱具有最高杀虫活性的不同侧穗过江藤（Lippia sidoides）基因型。本次研究所涉及的种质资源（germplasm）包括LSID006、LSID102、LSID103及LSID104。其中，以香芹酚为主要成分的LSID104基因型，其杀幼虫活性最差，半数致死浓度（LC50）为2.99 mg/mL。LSID006基因型对饱血雌蜱的杀虫效果最差，LC50为12.46 mg/mL，且其化学组成与LSID102基因型相似；而LSID102基因型展现出最高的杀蜱活性，LC50为2.81 mg/mL。本研究结论表明，侧穗过江藤种质资源的化学相似性与针对微小牛蜱的杀蜱活性并无关联。侧穗过江藤精油是一种高效天然活性物质，然而本研究结果为基于该天然产物的产品开发提供了更深入的认知，此类开发需协同考量化合物间的协同效应或次要成分的作用。