Entomology and Nematology Department, University of Florida, Gainesville, FL, 32611, USA.
Emerging Pathogens Institute, University of Florida, Gainesville, FL, 32611, USA.
J Med Entomol. 2022 May 11;59(3):922-929. doi: 10.1093/jme/tjac029.
Amblyomma americanum Linnaeus (Ixodida: Ixodidae) is ubiquitously present throughout the southeastern United States and is capable of vectoring several pathogens. White-tailed deer are the main host for adult A. americanum. However, this tick species is a generalist that will feed on most vertebrates, including humans, deer, livestock, and pets. Management of this species can be challenging due to a lack of cost-effective strategies. Acaricides are often utilized, however, this may lead to pesticide resistance. The Food and Agriculture Organization of the United Nations (FAO) larval packet test (LPT) was performed on susceptible A. americanum to determine the lethal concentration (LC) and discriminating concentration (DC) values for permethrin. The FAO LPT was used at these pre-established values to compare levels of resistance in ticks collected from a captive deer farm and wild areas representing high and low permethrin exposure settings, respectively. Resistance ratios (RR) calculated from the LC values for the ticks collected from farmed and wild deer ranged between 1 and 2. A. americanum collected from farmed and wild deer were not found to be resistant, however, some samples had slightly elevated RRs as compared to the susceptible laboratory strain, which may suggest tolerance development. Although the A. americanum sampled in this study were not resistant to permethrin, the DC calculated in this study will allow for rapid evaluation of resistance in a permethrin resistance monitoring program such that alternate management strategies can be adopted if resistance is detected.
美洲钝眼蜱（Amblyomma americanum Linnaeus）（蜱形目：硬蜱科）广泛存在于美国东南部，能够传播多种病原体。白尾鹿是美洲钝眼蜱成虫的主要宿主。然而，这种蜱类是一种多宿主物种，会叮咬包括人类、鹿、牲畜和宠物在内的大多数脊椎动物。由于缺乏经济有效的策略，这种物种的管理具有挑战性。通常会使用杀蜱剂，但这可能导致抗药性。为了确定氯菊酯的致死浓度（LC）和区分浓度（DC）值，对易感的美洲钝眼蜱进行了联合国粮食及农业组织（FAO）幼虫包测试（LPT）。使用 FAO LPT 在这些预先确定的值上比较了分别来自圈养鹿场和代表高和低拟除虫菊酯暴露环境的野外的蜱的抗药性水平。从来自圈养和野生鹿的蜱的 LC 值计算的抗性比（RR）在 1 到 2 之间。来自圈养和野生鹿的美洲钝眼蜱未被发现具有抗药性，但与敏感的实验室品系相比，一些样本的 RR 略有升高，这可能表明出现了耐药性。尽管本研究中采样的美洲钝眼蜱对拟除虫菊酯没有抗药性，但本研究中计算的 DC 将允许在拟除虫菊酯抗药性监测计划中快速评估抗药性，以便在检测到抗药性时采用替代管理策略。
