The intensive usage of chemical acaricides for the control of the cattle tick Rhipicephalus microplus has resulted in the development and establishment of multi-acaricide resistant populations. Fipronil, a phenylpyrazole insecticide, is currently marketed in India for the management of this important veterinary tick species. Here, we tested Indian isolates of R. microplus which have developed multi-acaricide resistance, for their susceptibility to fipronil. Twenty-five field isolates from five agro-climatic zones of the country were collected and tested by adult immersion test (AIT) and larval packet test (LPT). Sixteen isolates with resistance factor (RF) in the range of 1.56–10.9 were detected using LPT, whereas only 11 isolates with RF ranging from 1.05 to 4.1 were detected using AIT. A significant variation of RF between both tests was found, which raises doubt about the suitability of larva-based assays in screening of fipronil resistance. The data indicated possible cross-resistance between groups of acaricides in fipronil-resistant tick populations.

中文翻译：

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印度各州对氟虫腈耐药的微小头鼻hip的出现。

大量使用化学杀螨剂来控制牛R Rhipicephalus microplus导致了发展和建立了多种抗杀螨剂的种群。苯吡唑类杀虫剂氟虫腈目前在印度销售，用于管理这种重要的兽for。在这里，我们测试了印度R. microplus的分离株由于对氟虫腈的敏感性，已发展出对多种杀螨剂的抗性。收集了来自该国五个农业气候区的25个野外分离株，并通过成人浸没试验（AIT）和幼虫包试验（LPT）进行了测试。使用LPT检测到16株耐药因子（RF）在1.56-10.9之间的菌株，而使用AIT仅检测到11株RF在1.05至4.1之间的菌株。发现两个测试之间RF的显着变化，这使人们对基于幼虫的测定在筛选氟虫腈耐药性方面的适用性提出了疑问。数据表明耐氟虫腈的tick种群中的杀螨剂组之间可能有交叉耐药性。