Efficacy of extracts from plants of the Brazilian Pantanal against Rhipicephalus (Boophilus) microplus

This research evaluated the in vitro acaricidal activity of extracts from 21 plant species from the Pantanal of Mato Grosso do Sul. During stage I, a larval immersion test was performed using three extract concentrations (5%, 20%, and 40%). During stage II, we used only plants that showed over 95% efficiency at the 40% concentration in stage I in an amount sufficient for the adult immersion test. Aeschynomene denticulata, Angelonia hirta, Aspilia latissima, Caperonia castaneifolia, Centratherum punctatum, Crotalaria micans, Diodia kuntzei, Echinodorus paniculatus, Hyptis mutabilis, Lantana canescens, Melanthera latifolia, Ocotea diospyrifolia, Richardia grandiflora, Sebastiana hispida, Tocoyena formosa, Zanthoxylum rigidum, and Sesbania virgata (fruit extract) showed acaricidal activity against the larval stage of Rhipicephalus (Boophilus) microplus higher than 95% at a 40% (w/v) concentration, while Hippocratea volubilis and Randia armata showed moderate efficacy and Croton glandulosus and Senna obtusifolia had no effect. The M. latifolia, A. hirta, R. grandiflora, and A. latissima raw extracts were evaluated for their activity against adults, and only A. hirta showed an efficacy close to 90%. Eighteen extracts had an efficacy of up to 95% against larvae at a 40% concentration, seven extracts were effective at 20%, and only one (Sebastiana hispida) was effective at a 5% concentration.

本研究评估了取自南马托格罗索州潘塔纳尔（Pantanal）湿地的21种植物提取物的体外（in vitro）杀螨活性。试验第一阶段采用幼虫浸渍试验（larval immersion test），设置5%、20%、40%三种提取物浓度梯度。试验第二阶段仅选用第一阶段中40%浓度下杀螨效率超过95%的植物，且其用量需满足成虫浸渍试验（adult immersion test）的要求。
在40%（质量体积比，w/v）浓度下，以下植物提取物对微小扇头蜱（Rhipicephalus (Boophilus) microplus）幼虫期的杀螨活性高于95%：钝叶合萌（Aeschynomene denticulata）、硬毛天使花（Angelonia hirta）、宽叶阿斯皮利亚草（Aspilia latissima）、栗叶假苍耳（Caperonia castaneifolia）、斑点星苞菊（Centratherum punctatum）、亮叶猪屎豆（Crotalaria micans）、宽叶耳草（Diodia kuntzei）、圆锥刺果泽泻（Echinodorus paniculatus）、变叶香茶菜（Hyptis mutabilis）、灰毛马缨丹（Lantana canescens）、宽叶千日菊（Melanthera latifolia）、柿叶新木姜子（Ocotea diospyrifolia）、大花理查德草（Richardia grandiflora）、硬毛塞巴斯蒂安草（Sebastiana hispida）、美丽托科依纳木（Tocoyena formosa）、硬皮花椒（Zanthoxylum rigidum）以及Virgata田菁（Sesbania virgata，果实提取物）。此外，Hippocratea volubilis与Randia armata表现出中等杀螨活性，而Croton glandulosus与Senna obtusifolia则无杀螨效果。
研究人员对宽叶千日菊（Melanthera latifolia）、硬毛天使花（Angelonia hirta）、大花理查德草（Richardia grandiflora）及宽叶阿斯皮利亚草（Aspilia latissima）的粗提物进行了成虫杀螨活性评估，结果仅硬毛天使花的杀螨效率接近90%。
试验数据显示，18种提取物在40%浓度下对蜱幼虫的杀螨效率可达95%，7种提取物在20%浓度下表现出杀螨活性，仅硬毛塞巴斯蒂安草（Sebastiana hispida）一种提取物在5%浓度下具有杀螨效果。