Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology, Mississippi State University, Twelve Lane, Mississippi State, MS.
Department of Biological Sciences, St. Edward's University, Austin, TX.
J Med Entomol. 2020 Sep 7;57(5):1480-1487. doi: 10.1093/jme/tjaa077.
Environmental factors affect host-seeking behavior in ticks. In this study, 80 nymphal Amblyomma maculatum Koch were released in an observation arena containing four different heights of broomsedge stems (Andropogon virginicus L.) anchored in sand. Observations were made over three days as to proportion of ticks questing, questing height, and stem height distribution This scenario was replicated three times with different cohorts of ticks (n = 80 per replicate) for each of three treatment combinations of temperature and humidity: High temperature/high humidity (HTHH), high temperature/low humidity (HTLH), and low temperature/high humidity (LTHH). A fourth treatment utilizing the same size cohort and number of replicates included Wind (HTHHW+/-) by alternating days of wind and no-wind conditions over four days. Mean questing height for ticks under HTHH, HTLH, and LTHH conditions ranged from 4.45 to 6.03 cm with ticks questing significantly higher in HTHH. A significantly lower proportion ticks quested in HTLH (8.64%) than HTHH (14.06%) and LTHH (15.33%). In HTHH and LTHH, a significantly higher proportion of ticks were observed questing on 5-cm stems. Wind significantly reduced average questing height, and when absent, ticks on 20- and 30-cm stems quested significantly higher. These data indicate that A. macuatum nymphs randomly select stems to quest upon and climb upward until environmental conditions are prohibitive/ideal. Conditions with reduced vapor pressure deficit (VPD) led to higher questing frequency and height. Relatively low questing heights observed correspond with size of preferred hosts and may explain infrequency of collection by dragcloth in the field.
环境因素影响蜱的宿主寻找行为。在这项研究中，80 只幼龄孤星蜱被释放到一个观察场中，该观察场包含固定在沙中的四根不同高度的柳枝稷茎（Andropogon virginicus L.）。观察了三天，以确定蜱的求偶比例、求偶高度和茎的高度分布。这个场景用不同批次的蜱（每个重复 80 只）重复了三次，每个处理组合的温度和湿度都有三种：高温/高湿度（HTHH）、高温/低湿度（HTLH）和低温/高湿度（LTHH）。第四个处理利用相同大小的队列和重复次数，包括风（HTHHW+/-），在四天内交替进行风和无风条件。在 HTHH、HTLH 和 LTHH 条件下，蜱的平均求偶高度在 4.45 到 6.03 厘米之间，HTHH 下的蜱求偶高度明显更高。HTLH（8.64%）下的蜱求偶比例明显低于 HTHH（14.06%）和 LTHH（15.33%）。在 HTHH 和 LTHH 中，观察到更高比例的蜱在 5 厘米的茎上求偶。风显著降低了平均求偶高度，当没有风时，20 厘米和 30 厘米的茎上的蜱求偶高度明显更高。这些数据表明，孤星蜱幼蜱随机选择茎来求偶并向上攀爬，直到环境条件不利/理想。蒸汽压亏缺（VPD）降低的条件导致求偶频率和高度增加。观察到的相对较低的求偶高度与首选宿主的大小相对应，这可能解释了在野外用拖网收集蜱的频率较低。
