Brazilian spotted fever (BSF), caused by the bacterium Rickettsia rickettsii, is transmitted to humans mainly by the tick Amblyomma sculptum in southeastern Brazil. In most BSF-endemic areas A. sculptum populations are sustained chiefly by capybaras (Hydrochoerus hydrochaeris), which are also the host of another tick species, Amblyomma dubitatum, not implicated in R. rickettsii transmission. Herein, we evaluated the effects of relative humidity (RH), temperature, and water immersion on the successful development of the engorged stages of A. dubitatum and compared them with recently published data under the same experimental conditions for A. sculptum. We showed that free-living developmental stages (engorged larvae, nymphs and females, and eggs) of A. dubitatum had higher survival rates when these stages were submerged in water for different periods of times (24–72 h). On the other hand, higher survival rates were observed for A. sculptum when ticks were incubated at lower RH values, 65 or 78 %, regardless of summer or winter mean temperatures. These results suggest that A. dubitatum is more adapted to humid habitats and seasonally flooding soils than A. sculptum, whereas this latter species should be more adapted than A. dubitatum to drier habitats. The implications of these results for the spatial distribution of A. dubitatum and A. sculptum, in relation to BSF epidemiology, are discussed.

巴西立克次氏菌引起的巴西斑点热（BSF）主要通过巴西东南部的壁虱Amblyomma sculptum传播给人类。在大多数BSF流行地区，雕塑动物的种群主要由水豚维持，而水豚也是另外的tick类宿主-双盲mb（Amblyomma dubitatum）的宿主，不涉及立克次氏菌的传播。在这里，我们评估了相对湿度（RH），温度和浸水对杜鹃花红肿阶段成功发育的影响，并将它们与相同条件下相同条件下最新发表的数据进行了比较。A.雕塑 我们显示，当将这些阶段浸没在水中不同时间段（24-72小时）时，bitbitatum的自由生活发育阶段（饱足的幼虫，若虫和雌性以及卵）具有较高的存活率。另一方面，当summer在较低的RH值（65％或78％）下孵育时，无论夏季或冬季的平均温度如何，都可以观察到较高的成活率。这些结果表明，比起草假单胞菌，杜比丁草更适合于潮湿的生境和季节性洪水土壤，而后者比杜比丁香更适合于干燥的生境。这些结果对空间分布的影响讨论了与BSF流行病学有关的dubitatum和A. sculptum。