Singh Nirbhay K, Singh Harkirat, Mehta Nitin, Rath Shitanshu S
Department of Veterinary Parasitology, College of Veterinary Science, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab, 141004, India.
Department of Veterinary Parasitology, College of Veterinary Science, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab, 141004, India.
Exp Parasitol. 2019 Jun;201:42-48. doi: 10.1016/j.exppara.2019.04.007. Epub 2019 Apr 26.
Rhipicephalus (Boophilus) microplus (Acari: Ixodidae), is one of the most important ectoparasite of cattle, responsible for causing severe economic losses in the tropical and subtropical regions of the world. The development of resistance to most of the commonly used chemical acaricides has stimulated the search for new herbal products as an eco-friendly tick control alternative. The aim of the present study was to evaluate the in vitro acaricidal activity of essential oils (EOs) of cloves (Syzygium aromaticum), bark of cinnamon (Cinnamomum zeylanicum) and leaves of lemon grass (Cymbopogon citratus) against unfed larvae of R. (B.)microplus by larval packet test. Also, various combinations were prepared by mixing of equal concentrations of any two and all three EOs and used to study the effects of interactions of mixtures against larvae of R. (B.) microplus. The lethal concentrations at 50% (LC), 90% (LC) and 99% (LC) with 95% confidence limits (CL) were estimated by Probit analysis using PoloPlus. The computer software, CompuSyn, was used for determining the effects of interactions (synergistic, additive or antagonistic) of EO mixtures by calculation of Combination index (CI) and Dose-reduction index (DRI). Among the individual and mixture of two EOs, cinnamon EO and cinnamon EO + lemon grass EO combination showed highest acaricidal activity against R. (B.) microplus larvae. Further, the combination of cinnamon EO + lemon grass EO showed high synergism with CI value of 0.381, followed by cinnamon EO + clove EO showing moderate synergism whereas, clove EO + lemon grass EO showed only additive effect, with favorable dose reduction for each constituent drug in all three combinations. The combination of all three EOs (1:1:1) showed high synergism (CI value of 0.376) and favorable dose reduction (DRI index of 8.19, 25.64 and 4.64 for clove, cinnamon and lemon grass EOs, respectively) against R. (B.) microplus larvae.
微小牛蜱（蜱螨目：硬蜱科）是牛最重要的体外寄生虫之一，在世界热带和亚热带地区造成严重经济损失。对大多数常用化学杀螨剂产生抗药性，促使人们寻找新的草药产品作为一种生态友好型蜱虫控制替代品。本研究的目的是通过幼虫包囊试验，评估丁香（丁香）、肉桂树皮（锡兰肉桂）和柠檬草叶（香茅）精油对微小牛蜱未进食幼虫的体外杀螨活性。此外，通过将任意两种和所有三种精油等浓度混合制备各种组合，并用于研究混合物相互作用对微小牛蜱幼虫的影响。使用PoloPlus通过概率分析估计50%（LC）、90%（LC）和99%（LC）致死浓度及95%置信限（CL）。计算机软件CompuSyn用于通过计算组合指数（CI）和剂量减少指数（DRI）来确定精油混合物相互作用（协同、相加或拮抗）的影响。在单一精油和两种精油的混合物中，肉桂精油以及肉桂精油+柠檬草精油组合对微小牛蜱幼虫表现出最高的杀螨活性。此外，肉桂精油+柠檬草精油组合表现出高协同性，CI值为0.381，其次是肉桂精油+丁香精油表现出中等协同性，而丁香精油+柠檬草精油仅表现出相加效应，在所有三种组合中每种成分药物的剂量均有有利降低。三种精油（1:1:1）组合对微小牛蜱幼虫表现出高协同性（CI值为0.376）和有利的剂量降低（丁香、肉桂和柠檬草精油的DRI指数分别为8.19、25.64和4.64）。
