The cattle tick Rhipicephalus microplus affects animal production economically by reducing weight gain and milk production and causing diseases, such as babesiosis and anaplasmosis. Using synthetic acaricides to reduce their incidence has caused the emergence of resistant tick populations. The present study aimed to assess the in vitro acaricidal activity of combinations of essential oils (EOs) from Ocimum americanum, Ocimum gratissimum, and Lippia multiflora against R. microplus larvae. In fact, numerous biological properties have been reported on EOs from these three plants, including acaricidal properties. Hence, a larval immersion test was performed using a population of R. microplus resistant to synthetic acaricides used in Burkina Faso. Results revealed that EO from O. gratissimum was the most effective on R. microplus larvae with LC₅₀ and LC₉₀ values at 10.36 and 15.51 mg/mL, respectively. For EO combinations, the most significant synergistic effect was obtained by combination 6 (1/3 O. americanum + 2/3 O. gratissimum +1/6 L. multiflora), with a combination index value of 0.44. All combinations presented dose reduction index >1, indicating a favorable dose reduction. According to the literature, this is the first study to determine the combination effect of EOs from the abovementioned plants in controlling R. microplus activity in vitro. Thus, the combination of these EOs is an alternative to control the resistant populations of invasive cattle ticks.

牛蜱微小扇头蜱通过减少体重增加和产奶量并引起巴贝斯虫病和无形体病等疾病，对动物生产产生经济影响。使用合成杀螨剂来减少其发病率导致了抗性蜱种群的出现。本研究旨在评估美洲罗勒、无花罗勒和多花唇形花精油 (EO) 组合对小叶罗勒幼虫的体外杀螨活性。事实上，这三种植物的环氧乙烷具有多种生物特性，包括杀螨特性。因此，使用对布基纳法索使用的合成杀螨剂具有抗性的R. microplus群体进行了幼虫浸泡测试。结果显示，来自O. gratissimum的 EO 对R. microplus幼虫最有效，LC ₅₀和 LC ₉₀值分别为 10.36 和 15.51 mg/mL。EO组合中，组合6（1/3美洲O. americanum + 2/3 O. gratissimum + 1/6  L. multiflora）协同效应最显着，组合指数值为0.44。所有组合的剂量减少指数>1，表明剂量减少有利。根据文献，这是首次确定上述植物的EOs在体外控制R. microplus活性的组合效应。因此，这些 EO 的组合是控制入侵牛蜱的抗性种群的替代方案。