Calhoun D M, Leslie K L, Riepe T B, Achatz T J, McDevitt-Galles T, Tkach V V, Johnson P T J
Department of Ecology and Evolutionary Biology, University of Colorado, Ramaley N122 CB334, Boulder, CO 80309, USA.
Department of Biology, University of North Dakota, Grand Forks, ND 58202-9019, USA.
J Helminthol. 2019 Mar 4;94:e44. doi: 10.1017/S0022149X18001244.
Digenetic trematodes of the genus Clinostomum are cosmopolitan parasites infecting fishes, amphibians, reptiles, and snails as intermediate hosts. Despite the broad geographical distribution of this genus, debate about the number of species and how they vary in host use has persisted. To better understand patterns of infection among host species and across life stages, we used large-scale field surveys and molecular tools to examine five species of amphibians and seven species of fishes from 125 California ponds. Among the 12,360 examined hosts, infection was rare, with an overall prevalence of 1.7% in amphibians and 9.2% in fishes. Molecular evidence indicated that both groups were infected with Clinostomum marginatum. Using generalized linear mixed effects models, host species identity and host life stage had a strong influence on infection status, such that Lepomis cyanellus (green sunfish) (49.3%) and Taricha granulosa (rough skinned newt) (9.2%) supported the highest overall prevalence values, whereas adult amphibians tended to have a higher prevalence of infection relative to juveniles (13.3% and 2.5%, respectively). Experimentally, we tested the susceptibility of two amphibian hosts (Pseudacris regilla [Pacific chorus frog] and Anaxyrus boreas [western toad]) to varying levels of cercariae exposure and measured metacercariae growth over time. Pseudacris regilla was 1.3× more susceptible to infection, while infection success increased with cercariae exposure dose for both species. On average, metacarcariae size increased by 650% over 20 days. Our study highlights the importance of integrating field surveys, genetic tools, and experimental approaches to better understand the ecology of host-parasite interactions.
斜睾科的枝腺吸虫属是一种广泛分布的寄生虫，它以鱼类、两栖动物、爬行动物和蜗牛作为中间宿主。尽管该属寄生虫具有广泛的地理分布，但关于其物种数量以及宿主利用方式的差异一直存在争议。为了更好地了解宿主物种间以及不同生命阶段的感染模式，我们通过大规模的野外调查和分子工具，对来自加利福尼亚州125个池塘的5种两栖动物和7种鱼类进行了研究。在12360只被检查的宿主中，感染情况较为罕见，两栖动物的总体感染率为1.7%，鱼类为9.2%。分子证据表明，这两个群体均感染了边缘枝腺吸虫。使用广义线性混合效应模型分析发现，宿主物种身份和宿主生命阶段对感染状态有很大影响，其中蓝鳃太阳鱼（Lepomis cyanellus）（49.3%）和粗糙皮肤蝾螈（Taricha granulosa）（9.2%）的总体感染率最高，而成体两栖动物相对于幼体往往具有更高的感染率（分别为13.3%和2.5%）。在实验中，我们测试了两种两栖动物宿主（太平洋合唱蛙[Pseudacris regilla]和西部蟾蜍[Anaxyrus boreas]）对不同水平尾蚴暴露的易感性，并测量了随着时间推移囊蚴的生长情况。太平洋合唱蛙对感染的易感性是另一种的1.3倍，并且两种物种的感染成功率均随尾蚴暴露剂量的增加而提高。平均而言，囊蚴大小在20天内增加了650%。我们的研究强调了整合野外调查、遗传工具和实验方法对于更好地理解宿主 - 寄生虫相互作用生态学的重要性。
