Centre for Planetary Health and Food Security, Griffith University, Southport, QLD, Australia; Department of Biology, Truman State University, Kirksville, MO, USA.
Department of Biology, Truman State University, Kirksville, MO, USA.
Ticks Tick Borne Dis. 2022 Sep;13(5):101988. doi: 10.1016/j.ttbdis.2022.101988. Epub 2022 Jun 15.
Understanding the factors which influence host-seeking behavior of ticks is essential to determine the risk they pose as a vector of pathogens. While many studies have evaluated the impact of environmental variables on tick behavior, few have examined how seasonal changes in physiological status may further modify patterns of activity. In this study, we measured differences in questing behavior of mid spring- and early summer-caught Amblyomma americanum nymphs held under standardized laboratory conditions. As both groups represent the same cohort of overwintered nymphs, we hypothesized that age-related changes in the older summer ticks may influence questing behavior. In each season, we collected nymphs from field and forest habitats in northeast Missouri, after which we placed each nymph individually in a desiccating vertical questing apparatus with a hydrating microenvironment at the base. On the day following collection, we recorded the height of each nymph in the apparatus bi-hourly from 04:00 to 22:00 and calculated the vertical displacement between consecutive observations. Despite displaying no differences in mean questing height throughout the experiment, active ticks collected in the summer group (n = 89) travelled greater cumulative distances between desiccating and hydrating microenvironments than those collected in the spring (n = 119). This suggests that questing efficiency decreases in summer nymphs to accommodate increased time allocation towards rehydration. While we observed no direct association between body size and distance travelled, body size of the nymphal population also decreased significantly from spring to summer. Overall, our results demonstrate that there are seasonal changes in how A. americanum responds to environmental conditions. To more accurately predict host-seeking behavior of ticks across seasons, models should incorporate physiological parameters of the active ticks in a given population.
了解影响蜱寻找宿主行为的因素对于确定它们作为病原体传播媒介的风险至关重要。虽然许多研究已经评估了环境变量对蜱行为的影响，但很少有研究研究生理状态的季节性变化如何进一步改变活动模式。在这项研究中，我们测量了在标准化实验室条件下饲养的中春和初夏捕获的美洲钝缘蜱若虫的求偶行为差异。由于这两个群体代表同一批越冬若虫，我们假设年龄相关的夏季蜱变化可能会影响求偶行为。在每个季节，我们从密苏里州东北部的野外和森林栖息地收集若虫，然后将每个若虫单独放置在一个干燥的垂直求偶装置中，底部有一个保湿微环境。在收集后的第二天，我们每两小时从 04:00 到 22:00 记录装置中每个若虫的高度，并计算连续观察之间的垂直位移。尽管在整个实验过程中求偶高度没有差异，但在夏季采集的活跃蜱（n=89）在干燥和保湿微环境之间移动的累计距离大于春季采集的蜱（n=119）。这表明，夏季若虫的求偶效率降低，以适应增加的再水合时间分配。虽然我们没有观察到身体大小和移动距离之间的直接关联，但从春季到夏季，若虫种群的身体大小也显著减小。总的来说，我们的研究结果表明，A. americanum 对环境条件的反应存在季节性变化。为了更准确地预测蜱在不同季节的寻找宿主行为，模型应在给定种群中纳入活跃蜱的生理参数。
