在巴西的实验室和田间条件下，氟虫腈对微小牛蜱的杀螨效果。
Acaricidal efficacy of fluralaner against Rhipicephalus microplus ticks under laboratory and field conditions in Brazil.
作者信息
Rodrigues Daniel de Castro, Gomes Gabriel Webert, Vale Francisca Leticia, Teixeira Ana Lúcia Coutinho, Silva Isabela Santos, Chagas Haile Dean Figueiredo, Strydom Tom, Torres Siddartha, de Mendonça Rafael Paranhos, de Almeida Borges Fernando, Costa Junior Lívio, Ferreira Lorena Lopes, Lopes Welber Daniel Zanetti, Monteiro Caio
机构信息
Graduate Program in Animal Science-School of Veterinary and Animal Science, Federal University of Goiás-Samambaia Campus, Nova Veneza Highway, Km 8, Goiânia, GO, 74690-900, Brazil.
MSD Animal Health, Avenida Dr. Chucri Zaidan, 246-96, 9th Floor, São Paulo, SP, CEP 04583-110, Brazil.
出版信息
Parasit Vectors. 2025 Apr 28;18(1):161. doi: 10.1186/s13071-025-06775-2.
BACKGROUND
The first isoxazoline-based acaricide (fluralaner) for the control of Rhipicephalus microplus was introduced onto the market in 2022, initially in Brazil, followed by other Latin American countries. Therefore, it is important to establish laboratory methods to monitor the susceptibility of populations of R. microplus to this molecule and to determine the relationship between the results of laboratory tests and those from field trials.
METHODS
A larval immersion test (LIT) was performed on 18 populations of R. microplus. The lethal concentration 50 (concentration causing 50% mortality [LC50]) values were calculated to determine the resistance ratios (RRs) of the populations. The lethal concentration 99 (concentration causing 99% mortality [LC99]) values were calculated to determine the discriminating doses (DDs = 2 × LC99). The DDs were applied in tests with the POA (susceptible) and GYN (resistant) strains, as well as in tests with the population that presented the lowest LC50 value (population 14) and with the two populations that presented the highest LC50 value (populations 10 and 16). Finally, we performed field trials with the population that presented the lowest and two highest LC50 values.
RESULTS
In the LIT with fluralaner, the LC50 values ranged from 0.144 to 0.481 µg/mL for the 18 R. microplus populations. The mortality rate was 100% in the tests of the DDs in the five populations tested. In the field trials, the efficacy of fluralaner was similar for the three populations of R. microplus tested (populations 14, 10 and 16), with therapeutic efficacy (until day 21) of 100% and persistent efficacy (between days 28 and 42) > 95%.
CONCLUSION
We observed natural variability in the susceptibility of larvae from the different populations of R. microplus that had never been treated with this compound. Despite the observed variability in the in vitro results (LC50), a comparable efficacy of > 90% lasting until day 42 was observed in the field trials. Also, based on the results of the laboratory testing (LC50 and DD) and field trials, we can conclude that there was no resistance to fluralaner in the 18 studied tick populations.
背景
2022年，第一种用于控制微小扇头蜱的异恶唑啉类杀螨剂（氟虫腈）投放市场，最初在巴西，随后推广至其他拉丁美洲国家。因此，建立实验室方法以监测微小扇头蜱种群对该分子的敏感性，并确定实验室测试结果与田间试验结果之间的关系非常重要。
方法
对18个微小扇头蜱种群进行了幼虫浸渍试验（LIT）。计算致死浓度50（导致50%死亡率的浓度[LC50]）值以确定种群的抗性比率（RRs）。计算致死浓度99（导致99%死亡率的浓度[LC99]）值以确定区分剂量（DDs = 2×LC99）。将DDs应用于POA（敏感）和GYN（抗性）品系的测试，以及LC50值最低的种群（种群14）和LC50值最高的两个种群（种群10和16）的测试。最后，我们对LC50值最低和最高的两个种群进行了田间试验。
结果
在使用氟虫腈的LIT中，18个微小扇头蜱种群的LC50值范围为0.144至0.481μg/mL。在测试的五个种群中，DDs测试的死亡率为100%。在田间试验中，测试的三个微小扇头蜱种群（种群14、10和16）对氟虫腈的疗效相似，治疗效果（至第21天）为100%，持续效果（第28天至42天之间）> 95%。
结论
我们观察到从未接触过该化合物的不同微小扇头蜱种群幼虫的敏感性存在自然差异。尽管体外结果（LC50）存在差异，但在田间试验中观察到持续至第42天的疗效> 90%。此外，根据实验室测试（LC50和DD）和田间试验的结果，我们可以得出结论，在研究的18个蜱种群中，未发现对氟虫腈有抗性。
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