Eco-Epidemiology Group, Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium; Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Diepenbeek, Belgium.
Evolutionary Ecology Group, Department of Biology, University of Antwerp, Wilrijk, Belgium.
Ticks Tick Borne Dis. 2022 Jul;13(4):101966. doi: 10.1016/j.ttbdis.2022.101966. Epub 2022 May 13.
In non-permanent parasites, host detachment should take place in an environment that ensures the continuation of their life cycle. Timing of detachment - in combination with the host's space use - affects dispersal and transmission success of the parasites and of the pathogens they vector. Before reaching the adult reproductive stage, ticks need to go through multiple immature developmental stages (larva and nymph), each feeding on host blood. In between the feeding bouts, they often remain in the off-host environment for considerable periods of time. With this study, we aimed to obtain more insight in Ixodes frontalis' off-host habitat use by comparing its detachment pattern in different life stages with that of two habitat-specialized ticks also found on birds: the endophilic tree-hole tick (Ixodes arboricola) and the exophilic sheep tick (Ixodes ricinus), the latter living in humid understory vegetation of forests. For this, we artificially infested hole-roosting (great tits, Parus major) and open-roosting (blackbirds, Turdus merula) birds with ticks under laboratory conditions, and recorded whether detachment occurred during the day or the night. We hypothesize that nocturnal detachment improves off-host mating opportunities and host localization, whereas diurnal detachment optimizes tick dispersal. Ixodes frontalis nymphs detached during the night, especially when feeding on blackbirds. This behaviour was very similar to that of I. arboricola (larva and nymph) feeding on great tits. In contrast, I. frontalis larvae detached during the day, especially when feeding on great tits, which resembles that of I. ricinus' feeding behaviour (larva and nymph). Ixodes frontalis left the host within seven days, immediately after completion of the blood meal. This is similar to both developmental stages of I. ricinus but contrasts with the very long (up to 20 days) feeding duration in I. arboricola. Thus I. frontalis shows strong plasticity, switching from dispersal-centered (larvae) to host-centered (nymphs) detachment behaviour. Findings are discussed with regard to the ticks' habitat use, dispersal, life history and host specificity.
在非永久性寄生虫中，宿主的脱离应该发生在一个确保其生命周期延续的环境中。脱离的时间——结合宿主的空间利用——会影响寄生虫和它们传播的病原体的扩散和传播成功率。在达到成年生殖阶段之前，蜱需要经历多个不成熟的发育阶段（幼虫和若虫），每个阶段都以宿主的血液为食。在进食之间，它们经常在离开宿主的环境中停留相当长的时间。通过这项研究，我们旨在通过比较不同生活阶段的伊氏革蜱的脱离模式与两种也在鸟类上发现的栖息地专业化蜱的脱离模式，来更深入地了解伊氏革蜱的离宿主栖息地利用情况：内栖树洞蜱（Ixodes arboricola）和外栖绵羊蜱（Ixodes ricinus），后者生活在森林潮湿的林下植被中。为此，我们在实验室条件下用蜱人工感染树洞栖息（大山雀，Parus major）和开阔地栖息（黑鸟， Turdus merula）的鸟类，并记录它们是在白天还是夜间脱离。我们假设夜间脱离可以改善离宿主交配机会和宿主定位，而白天脱离则可以优化蜱的扩散。伊氏革蜱若虫在夜间脱离，尤其是在以黑鸟为食时。这种行为与在大山雀上以食的伊氏革蜱（幼虫和若虫）非常相似。相比之下，伊氏革蜱幼虫在白天脱离，尤其是在以大山雀为食时，这与伊氏绵羊蜱的进食行为（幼虫和若虫）相似。伊氏革蜱在完成吸血后 7 天内离开宿主。这与伊氏绵羊蜱的两个发育阶段相似，但与伊氏树洞蜱的非常长的（长达 20 天）进食时间形成对比。因此，伊氏革蜱表现出很强的可塑性，从以扩散为中心（幼虫）的行为转变为以宿主为中心（若虫）的脱离行为。研究结果从蜱的栖息地利用、扩散、生活史和宿主特异性等方面进行了讨论。
