Lefcort Hugh, Brockman Sean M, Hopkins Jaxon W, Salter Sierra M
Biology Department, Gonzaga University, 502 E. Boone Avenue, Spokane, WA, 99258, USA.
Exp Appl Acarol. 2025 Jul 9;95(2):14. doi: 10.1007/s10493-025-01041-7.
Understanding how vector species such as ticks respond behaviorally to thermal and host-related cues is critical for predicting the effects of climate change on disease transmission. Ticks employ distinct questing strategies-ranging from static sit-and-wait behavior to active host seeking-that influence their exposure to abiotic stressors. We investigated whether Dermacentor andersoni and Dermacentor similis, two sit-and-wait tick species native to Eastern Washington, USA, exhibit behavioral plasticity in response to temperature gradients and host stimuli. We conducted three experiments to assess (1) thermal preferences of D. andersoni under host (dog) scent conditions, (2) thermotactic responses of both species to infrared (IR) radiation in the presence of dog odor, and (3) D. andersoni's approach behavior toward human hosts at various distances, i.e., a host emitting a combination of IR, CO, and odors. In thermal gradient assays, D. andersoni showed significantly increased movement toward warmer zones following CO₂ exposure and exhibited wide thermal preferences depending on specific dog odors. However, when exposed to an IR source, we found strong sit-and-wait behaviors by D. andersoni and D. similis regardless of temperature or radiation. The ticks were not attracted to infrared radiation and did not move toward the stationary exposed hand of an observer. Ticks may prioritize optimal locations to encounter potential hosts, over enzymatically optimal temperatures. Rather than evolving to detect hosts at a distance, Haller's organs may have evolved to differentiate warm attachment sites from cooler fur. Our results suggest that Dermacentor questing behavior (remaining on station despite a different preferred temperature) may make them particularly vulnerable to future rises in temperature.
了解蜱虫等病媒物种如何对温度和宿主相关线索做出行为反应，对于预测气候变化对疾病传播的影响至关重要。蜱虫采用不同的搜寻策略——从静态坐等行为到主动寻找宿主——这会影响它们暴露于非生物应激源的程度。我们研究了美国华盛顿州东部本土的两种坐等蜱虫物种，即安德逊革蜱（Dermacentor andersoni）和草原革蜱（Dermacentor similis），是否会对温度梯度和宿主刺激表现出行为可塑性。我们进行了三项实验，以评估：（1）安德逊革蜱在宿主（狗）气味条件下的热偏好；（2）两种蜱虫在有狗气味存在时对红外（IR）辐射的趋温反应；（3）安德逊革蜱在不同距离下对人类宿主的接近行为，即宿主散发红外、二氧化碳和气味的组合。在热梯度试验中，暴露于二氧化碳后，安德逊革蜱向较温暖区域的移动显著增加，并根据特定的狗气味表现出广泛的热偏好。然而，当暴露于红外源时，我们发现安德逊革蜱和草原革蜱无论温度或辐射如何，都表现出强烈的坐等行为。蜱虫不会被红外辐射吸引，也不会朝着观察者静止伸出的手移动。蜱虫可能会优先选择遇到潜在宿主的最佳位置，而不是酶促反应的最佳温度。哈勒氏器官可能不是进化为在远处检测宿主，而是进化为区分温暖的附着部位和较凉的皮毛。我们的结果表明，革蜱的搜寻行为（尽管偏好温度不同但仍停留在原地）可能使它们特别容易受到未来气温上升的影响。
