The current study investigated the synergistic effect of combinations containing deltamethrin (D), Eucalyptus essential oil (E), and the thyme essential oil component thymol (T), against a field population of Rhipicephalus annulatus in Egypt that was characterized to be resistant to D. Solutions of T, E, or TE at concentrations of 1.25–5% were combined with 5% deltamethrin at different dilutions (0.25–2 mL/L). Results of the adult immersion test used to estimate the in vitro acaricidal activity of these combinations at 5% yielded LC₅₀ values for D, E-D, T-D, and TE-D of 3.87 mL/L, 3.89 mL/L, 0.14 mL/L, and 0.05 mL/L, respectively. Biochemical analyses using whole-body homogenate of ticks from the in vitro tests revealed that the lowest acetylcholinesterase and glutathione peroxidase activity, and the maximum lipid peroxidation were recorded in ticks treated with 5% TE-D. Glutathione content significantly decreased (p ≤ 0.05) in all treated ticks. Three groups, each containing five cross breed cattle naturally infested with R. annulatus from the same area where resistance to D was detected, were sprayed twice at two-week intervals using 1 mL/L of 5% solutions of D, T-D, or TE-D. Overall efficacy of the D, T-D, and TE-D sprays by day 30 post-treatment was 21.6, 88.3, and 95 %, respectively. Ticks collected from infested cattle three days after treatment with the D spray deposited egg masses that were able to hatch, deposited small masses of eggs unable to hatch when exposed to the T-D spray, and laid few eggs that didn’t hatch when sprayed with the TE-D combination. Values for liver and kidney function parameters were comparable in cattle before and after treatment with the combination sprays tested. The TE-D spray overcame the insensitivity to D of this R. annulatus population in Egypt, which also highlighted the significant synergistic effect of thymol on the acaricidal activity of deltamethrin observed in vitro. Acaricidal activity of the TE-D combination apparently has deleterious effects on multiple tick systems involving inhibition of acetylcholinesterase, increased lipid peroxidation, and oxidative stress. These findings document that combinations of natural and synthetic products can be part of integrated management solutions to the problem with widespread resistance to pyrethroids like deltamethrin in populations of cattle ticks, including R. annulatus, around the world.

目前的研究调查了含有溴氰菊酯 (D)、桉树精油 (E) 和百里香精油成分百里香酚 (T) 的组合对埃及的环状 Rhipicephalus野外种群的协同作用，该种群的特征是对 D 具有抗性. 浓度为 1.25–5% 的 T、E 或 TE 溶液与不同稀释度 (0.25–2 mL/L) 的 5% 溴氰菊酯混合。用于估计这些组合在 5% 时的体外杀螨活性的成人浸泡试验的结果产生的 D、ED、TD 和 TE-D 的LC ₅₀值为 3.87 mL/L、3.89 mL/L、0.14 mL/L和 0.05 mL/L。使用体外蜱的全身匀浆进行生化分析测试表明，在用 5% TE-D 处理的蜱中记录到的乙酰胆碱酯酶和谷胱甘肽过氧化物酶活性最低，脂质过氧化最高。在所有处理过的蜱中，谷胱甘肽含量显着降低 ( p ≤ 0.05 )。三组，每组包含五头杂交牛，自然感染了R. annulatus从检测到 D 抗性的同一区域，使用 1 mL/L 的 5% D、TD 或 TE-D 溶液以两周的间隔喷洒两次。到治疗后第 30 天，D、TD 和 TE-D 喷雾剂的总体功效分别为 21.6、88.3 和 95%。用 D 喷剂处理三天后，从受感染的牛身上收集的蜱沉积了能够孵化的卵块，当暴露于 TD 喷剂时沉积了无法孵化的小块卵，并且在喷洒了TE-D 组合。在用测试的组合喷雾剂治疗之前和之后，牛的肝和肾功能参数值是可比的。TE-D 喷雾克服了这种R. annulatus对 D 的不敏感性埃及的人口，这也突出了百里酚对体外观察到的溴氰菊酯杀螨活性的显着协同作用。TE-D 组合的杀螨活性显然对多个蜱系统具有有害影响，包括抑制乙​​酰胆碱酯酶、增加脂质过氧化和氧化应激。这些发现证明，天然和合成产品的组合可以成为综合管理解决方案的一部分，以解决世界各地牛蜱（包括R. annulatus ）对溴氰菊酯等拟除虫菊酯的广泛耐药性问题。