Pyrethroid resistance has been a major hurdle limiting the effective control of bed bugs (Cimex lectularius L.). Alternative approaches that include the use of plant essential oils (EOs) have been proposed for effective management of bed bugs. However, EO resistance level comparisons between pyrethroid susceptible and resistant bed bug populations have not been previously conducted. The goal of this study was twofold: (i) determine deltamethrin resistance levels and associated resistance mechanisms in the field-collected Knoxville strain and (ii) quantify resistance levels of the Knoxville strain to five EOs (thyme, oregano, clove, geranium and coriander), their major insecticidal constituents (thymol, carvacrol, eugenol, geraniol and linalool) and an EO-based product (EcoRaider®). First, we found that the Knoxville strain was 72,893 and 291,626 fold more resistant to topically applied deltamethrin in comparison to the susceptible Harlan strain at the LD25 and LD50 lethal dose levels, respectively. Synergist bioassays and detoxification enzyme assays revealed significantly higher activity of cytochrome P450 and esterase enzymes in the resistant Knoxville strain. Further, Sanger sequencing revealed the presence of the L925I mutation in the voltage-sensitive sodium channel α subunit gene. The Knoxville strain that possesses both enzymatic and target site deltamethrin resistance, however, did not show any resistance to EOs, their major insecticidal constituents and EcoRaider® in topical bioassays (resistance ratio of ~1). In conclusion, this study demonstrated that a deltamethrin-resistant strain of bed bugs is susceptible to EOs and their insecticidal constituents.

中文翻译：

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表现出代谢和靶位点溴氰菊酯抗性的臭虫 Cimex lectularius L. 对植物精油敏感

拟除虫菊酯抗性一直是限制有效控制臭虫（Cimex lectularius L.）的主要障碍。已经提出了包括使用植物精油 (EO) 在内的替代方法来有效管理臭虫。然而，之前尚未对拟除虫菊酯易感和抗性臭虫种群之间的 EO 抗性水平进行比较。本研究的目标有两个：(i) 确定田间收集的诺克斯维尔菌株中溴氰菊酯的耐药水平和相关的耐药机制，以及 (ii) 量化诺克斯维尔菌株对五种 EO（百里香、牛至、丁香、天竺葵和香菜）的耐药水平)、它们的主要杀虫成分（百里酚、香芹酚、丁香酚、香叶醇和芳樟醇）和基于 EO 的产品 (EcoRaider®)。首先，我们发现诺克斯维尔菌株为 72,893 和 291，在 LD25 和 LD50 致死剂量水平下，与敏感的 Harlan 菌株相比，对局部应用的溴氰菊酯的抗性高 626 倍。增效剂生物测定和解毒酶测定显示，在抗性诺克斯维尔菌株中细胞色素 P450 和酯酶的活性显着更高。此外，Sanger 测序揭示了电压敏感钠通道 α 亚基基因中存在 L925I 突变。然而，同时具有酶促和靶位点溴氰菊酯抗性的 Knoxville 菌株在局部生物测定中未显示对 EO、其主要杀虫成分和 EcoRaider® 的任何抗性（抗性比约为 1）。总之，这项研究表明，一种耐溴氰菊酯的臭虫菌株对 EO 及其杀虫成分敏感。