Due to climate change-induced alterations of temperature and humidity, the distribution of pathogen-carrying organisms such as ticks may shift. Tick survival is often limited by environmental factors such as dryness, but a predicted hotter and wetter world may allow the expansion of tick ranges. Dermacentor andersoni and D. variabilis ticks are morphologically similar, co-occur throughout the Inland Northwest of Washington State, U.S.A., and both can be injected with pathogenic Rickettsia and Francisella bacteria. Differences in behavior and the potential role of endosymbiotic Rickettsia and Francisella in these ticks are poorly studied. We wanted to measure behavioral and ecological differences between the two species and determine which, if any, Rickettsia and Francisella bacteria – pathogenic or endosymbiotic - they carried. Additionally, we wanted to determine if either tick species may be selected for if the climate in eastern Washington becomes wetter or dryer. We found that D. andersoni is more resistant to desiccation, but both species share similar questing behaviors such as climbing and attraction to bright light. Both also avoid the odor of eucalyptus and DEET but not permethrin. Although both tick species are capable of transmitting pathogenic species of Francisella and Rickettsia, which cause tularemia and Rocky Mountain Spotted Fever, respectively, we found primarily non-pathogenic endosymbiotic strains of Francisella and Rickettsia, and only one tick infected with F. tularensis subspecies holarctica.

中文翻译：

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两种潜在的土拉菌病和落基山斑疹热蜱载体的行为特征和内共生体

由于气候变化引起的温度和湿度变化，蜱等病原体携带生物的分布可能会发生变化。蜱虫的生存通常受到干燥等环境因素的限制，但预测的更热和更潮湿的世界可能会扩大蜱虫的范围。Dermacentor andersoni和D. variabilis蜱在形态上相似，在美国华盛顿州西北部内陆地区同时出现，两者都可以注射致病性立克次体和弗朗西斯菌。内共生立克次氏体和弗朗西斯氏菌的行为差异和潜在作用在这些蜱虫研究很少。我们想测量这两个物种之间的行为和生态差异，并确定它们携带的立克次体和弗朗西斯菌（致病菌或内共生菌）（如果有的话）。此外，我们想确定如果华盛顿东部的气候变得更潮湿或更干燥，是否可以选择任一蜱种。我们发现D. andersoni对干燥的抵抗力更强，但两个物种都有相似的探索行为，例如攀爬和对强光的吸引力。两者都可以避免桉树和避蚊胺的气味，但不能避免氯菊酯。虽然这两种蜱虫都能够传播弗朗西斯氏菌和立克次氏体的致病物种，分别引起土拉菌病和落基山斑疹热，我们发现主要是弗朗西斯菌和立克次体的非致病性内共生菌株，并且只有一种蜱感染了土拉菌亚种holarctica。