Deep Sequencing of Pyrethroid-Resistant Bed Bugs Reveals Multiple Mechanisms of Resistance within a Single Population

A frightening resurgence of bed bug infestations has occurred over the last 10 years in the U.S. and current chemical methods have been inadequate for controlling this pest due to widespread insecticide resistance. Little is known about the mechanisms of resistance present in U.S. bed bug populations, making it extremely difficult to develop intelligent strategies for their control. We have identified bed bugs collected in Richmond, VA which exhibit both kdr-type (L925I) and metabolic resistance to pyrethroid insecticides. Using LD50 bioassays, we determined that resistance ratios for Richmond strain bed bugs were ∼5200-fold to the insecticide deltamethrin. To identify metabolic genes potentially involved in the detoxification of pyrethroids, we performed deep-sequencing of the adult bed bug transcriptome, obtaining more than 2.5 million reads on the 454 titanium platform. Following assembly, analysis of newly identified gene transcripts in both Harlan (susceptible) and Richmond (resistant) bed bugs revealed several candidate cytochrome P450 and carboxylesterase genes which were significantly over-expressed in the resistant strain, consistent with the idea of increased metabolic resistance. These data will accelerate efforts to understand the biochemical basis for insecticide resistance in bed bugs, and provide molecular markers to assist in the surveillance of metabolic resistance.

过去十年间，美国臭虫（bed bug）侵害出现了令人警惕的死灰复燃态势；由于臭虫已普遍产生杀虫剂抗药性，当前的化学防治手段难以有效管控该虫害。目前学界对美国臭虫种群的抗药性机制知之甚少，极大阻碍了针对性防治策略的研发。我们在弗吉尼亚州里士满采集的臭虫样本中，发现其对拟除虫菊酯类杀虫剂同时存在击倒抗性（kdr）型（L925I）与代谢抗性。通过半数致死剂量（LD50）生物测定实验，我们测得里士满品系臭虫对溴氰菊酯的抗药性倍数约为5200倍。为筛选潜在参与拟除虫菊酯类杀虫剂解毒代谢的功能基因，我们对成虫臭虫的转录组进行深度测序，在454钛金测序平台上获得了超250万条读段（reads）。完成序列组装后，我们对敏感品系哈兰（Harlan）与抗性品系里士满臭虫中新鉴定到的基因转录本进行分析，发现多个候选细胞色素P450基因与羧酸酯酶基因在抗性品系中显著上调表达，这与代谢抗性增强的假说相符。本数据集将助力学界深入解析臭虫杀虫剂抗药性的生化机制，并为代谢抗性的监测提供分子标记工具。