Department of Biology, University of Turku, FI-20014, Turku, Finland.
Biodiversity Unit, University of Turku, Turku, Finland.
Exp Appl Acarol. 2020 Dec;82(4):571-585. doi: 10.1007/s10493-020-00564-5. Epub 2020 Oct 31.
Hard ticks (Acari: Ixodidae) act as important vectors of zoonotic pathogens. For instance, Borrelia burgdorferi s.l. spirochetes pose a severe health risk as aetiological agents of Lyme borreliosis. Commonly, to study the abundance of questing (host-seeking) ticks, a 1 m piece of cloth is dragged over vegetation for a determined distance. Here, we designed a tick-sampling study to estimate the sampling efficiency of this standard method. We established 10 m dragging transects in a hemiboreal mixed forest patch in SW Finland for a 5-day monitoring period. Five of the transects were cloth-dragged 3× a day, whereas another five transects were dragged 6× a day in a manner that after each morning, midday and afternoon dragging, a second dragging was conducted on the same transect immediately. Captured Ixodes ricinus ticks were subsequently analysed for tick-borne pathogens. The initial population size of nymphal ticks on a transect was approximated by the accumulated nymph catch from the dragging sessions. The sampling efficiency of the cloth dragging was low, as a single dragging in a previously untouched vegetation strip always caught less than 12% (mean 6%) of the estimated population of active nymphs that were assumed to be questing during the study. Clear results were not found for daily activity rhythm, as ticks were caught in all daily dragging sessions. Approximately every third nymph and every second adult carried a pathogen, but nothing indicated that the occurrence of a pathogen affected the likelihood of the tick being caught by cloth dragging. Our results suggest that only a minority of active ticks can be caught by a single cloth dragging. The abundance estimates in many tick investigations might thus be downward biased.
硬蜱（蜱螨目：硬蜱科）是重要的人畜共患病病原体的载体。例如，伯氏疏螺旋体螺旋体作为莱姆病的病原体，构成了严重的健康风险。通常，为了研究（宿主寻找）游离蜱的丰度，会用 1 米长的布在植被上拖过一段确定的距离。在这里，我们设计了一项蜱采样研究，以估计这种标准方法的采样效率。我们在芬兰西南部的一个半湿润混合林斑块中建立了 10 米长的拖动样带，进行了为期 5 天的监测。其中 5 个样带每天拖动 3 次，而另外 5 个样带每天拖动 6 次，即每天早上、中午和下午拖动后，立即在同一样带上进行第二次拖动。随后对捕获的蓖子硬蜱进行了 tick-borne 病原体分析。通过拖动期间的幼虫累积捕获量，近似估算了样带上幼虫的初始种群规模。布拖曳的采样效率很低，因为在之前未被触及的植被带中进行单次拖动，总是捕获不到估计的活动幼虫种群的 12%（平均值为 6%），这些幼虫被认为是在研究期间在寻找宿主。由于在所有每日拖动中都捕获了蜱，因此未发现明确的每日活动节律结果。大约每 3 只幼虫和每 2 只成虫携带一种病原体，但没有迹象表明病原体的存在会影响蜱被布拖曳捕获的可能性。我们的研究结果表明，只有少数活动蜱可以通过单次布拖捕获。因此，许多蜱调查中的丰度估计可能会偏低。
