Evolutionary Ecology Group, Department of Biology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerpen, Belgium.
Parasitology. 2012 May;139(6):766-73. doi: 10.1017/S0031182011002277. Epub 2012 Jan 5.
Parasites exposed to fast-developing hosts experience a variety of conditions over a short time period. Only few studies in vertebrate-ectoparasite systems have integrated the timing of ectoparasite infestations in the host's development into the search for factors explaining ectoparasite burden. In this study we examined the temporal pattern of attachment in a nidicolous tick (Ixodes arboricola) throughout the development of a songbird (Parus major). In the first experiment, we exposed bird clutches at hatching to a mix of the 3 tick instars (larvae, nymphs and adults), and monitored the ticks that attached in relation to the average broods' age. In a complementary experiment we focused on the attachment in adult female ticks--the largest and most significant instar for the species' reproduction--after releasing them at different moments in the nestlings' development. Our observations revealed a positive association between the size of the attached instar and the broods' age. Particularly, adult females were less likely to be found attached to recently hatched nestlings, which contrasts with the smaller-sized larvae and nymphs. These differences suggest either an infestation strategy that is adapted to host physiology and development, or a result of selection by the hosts' anti-tick resistance mechanisms. We discuss the implications of our results in terms of tick life-history strategies.
寄生虫暴露于快速发育的宿主时，会在短时间内经历各种情况。在脊椎动物-外寄生虫系统中，只有少数研究将外寄生虫在宿主发育过程中的寄生时间纳入到寻找解释外寄生虫负担的因素的研究中。在这项研究中，我们研究了一种栖息在鸟巢中的蜱虫（Ixodes arboricola）在鸣禽（Parus major）发育过程中的附着时间模式。在第一个实验中，我们在孵化时将鸟卵暴露于 3 个蜱虫龄期（幼虫、若虫和成虫）的混合物中，并监测附着在平均雏鸟年龄的蜱虫。在一个补充实验中，我们在巢中雏鸟发育的不同时间释放成年雌性蜱虫（该物种繁殖中最大和最重要的龄期），并专注于它们的附着情况。我们的观察结果表明，附着的龄期大小与雏鸟的年龄之间存在正相关关系。特别是，成年雌性蜱虫不太可能附着在最近孵化的雏鸟身上，这与较小的幼虫和若虫形成鲜明对比。这些差异表明，寄生策略适应于宿主的生理和发育，或者是宿主抗蜱虫抵抗机制选择的结果。我们根据我们的研究结果讨论了蜱虫生活史策略的意义。
