The aim of this work was to adapt and apply the in vitro larval bioassay packet test (LPT) to diagnose resistance of Rhipicephalus microplus ticks to fipronil in Argentina. Ten serial dilutions of fipronil were included in the LPT bioassay. Seven populations of R. microplus from six Argentinean Provinces were evaluated. Samples from Colonia Benítez, Quimilí and Intiyaco were unambiguously classified in the category ‘resistant’. In all these cases the 95% confidence intervals did not overlap with that of the susceptible reference strain and the slope values were lower than the slope value obtained for the susceptible reference strain. The resistance ratio (RR₅₀) values of the populations from Colonia Benítez I and II, Quimilí and Intiyaco were 2.23, 3.49, 6.84 and 3.39, respectively. Populations from El Colorado I and II, Acambuco, Vera and Feliciano were classified as ‘susceptible’ because the 95% confidence intervals overlapped with that of the susceptible reference strain and the RR₅₀ values never exceeded 1.32. The results of these LPT bioassays indicate the presence of fipronil resistant R. microplus populations in Argentina.

这项工作的目的是适应和应用体外幼虫生物测定数据包测试（LPT）来诊断阿根廷微小头虱对氟虫腈的抗药性。LPT生物测定包括十种系列的氟虫腈稀释液。评价了来自六个阿根廷省的七个小核糖菌种群。来自科洛尼亚·贝尼特斯（ColoniaBenítez），基米利（Quimili）和因蒂亚科（Intiyaco）的样品被明确归类为“抗药性”类别。在所有这些情况下，95％置信区间与敏感参考应变的置信区间不重叠，并且斜率值低于为敏感参考应变获得的斜率值。电阻比（RR ₅₀）来自贝尼特斯一世和二世，基米利和因蒂亚科的人口分别为2.23、3.49、6.84和3.39。来自El Colorado I和II，Acambuco，Vera和Feliciano的人群被归类为“易感”人群，因为95％置信区间与易感参考菌株的区间重叠，并且RR ₅₀值从未超过1.32。这些LPT生物测定的结果表明在阿根廷存在对氟虫腈抗性的微小芽孢杆菌种群。