School of Biological Sciences, Washington State University, P.O. Box 644236, Pullman, WA 99164-4236, USA.
J Med Entomol. 2011 Jul;48(4):860-6. doi: 10.1603/me10256.
The blacklegged tick (Ixodes scapularis) is an important vector of emerging human pathogens. It has three blood-feeding stages, as follows: larva, nymph, and adult. Owing to inefficient transovarial transmission, at least for the Lyme disease agent (Borrelia burgdorferi), larval ticks rarely hatch infected, but they can acquire infection during their larval blood meal. Nymphal ticks are primarily responsible for transmitting pathogens to hosts, including humans. The transition from uninfected host-seeking larva to infectious host-seeking nymph is therefore a key aspect of human risk of infection. It can be divided into a series of steps, as follows: finding a host, taking a blood meal, becoming infected, molting, and overwintering. The chance of succeeding in each of these steps may depend on the species identity of the blood meal host. We used a Bayesian method to estimate the molting success of larval I. scapularis collected from four commonly parasitized species of birds and eight commonly parasitized small and mid-sized mammals found in the forests of Dutchess County, New York. We show that molting success varies substantially among host species; white-footed mice, veeries, and gray catbirds support particularly high molting success, whereas ticks feeding on short-tailed shrews, robins, and wood thrushes were less successful. We also show that larval molting success varies substantially between individual blood meal hosts, and that this intraspecific variability is much higher in some species than in others. The causes of both inter- and intraspecific variation in molting success remain to be determined.
黑腿蜱（Ixodes scapularis）是一种重要的新兴人类病原体传播媒介。它有三个吸血阶段，如下：幼虫、若虫和成虫。由于转卵传播效率低下，至少对于莱姆病病原体（Borrelia burgdorferi）而言，幼虫很少孵化感染，但它们可以在幼虫期的吸血过程中获得感染。若虫主要负责将病原体传播给宿主，包括人类。因此，从未感染的宿主寻找幼虫到感染的宿主寻找若虫的转变是人类感染风险的关键方面。它可以分为一系列步骤，如下：寻找宿主、吸血、感染、蜕皮和越冬。在这些步骤中的每一步中成功的机会可能取决于宿主血液的物种身份。我们使用贝叶斯方法估计了在纽约州达奇斯县森林中从四种常见寄生鸟类和八种常见寄生小型和中型哺乳动物中收集的幼虫黑腿蜱的蜕皮成功率。我们表明，蜕皮成功率在宿主物种之间存在显著差异；白足鼠、美洲知更鸟和灰猫鸟支持特别高的蜕皮成功率，而吸食短尾鼩、知更鸟和画眉的蜱虫则不太成功。我们还表明，幼虫蜕皮成功率在个体宿主血液中存在显著差异，而且这种种内变异性在某些物种中比在其他物种中更高。蜕皮成功率的种间和种内变异的原因仍有待确定。
