Institute of Parasitology, Biology Centre, Czech Academy of Sciences, 37005České Budějovice, Czech Republic.
Cavanilles Institute for Biodiversity and Evolutionary Biology, Science Park, University of Valencia, P.O. Box 22085, 46071Valencia, Spain.
Parasitology. 2022 Apr;149(4):457-468. doi: 10.1017/S0031182021002006. Epub 2021 Nov 11.
Cercarial activity and survival are crucial traits for the transmission of trematodes. Temperature is particularly important, as faster depletion of limited cercarial energy reserves occurs at high temperatures. Seasonal climate conditions in high latitude regions may be challenging to complete trematode life cycle during the 6-month ice-free period, but temperature effects on the activity and survival of freshwater cercariae have not been previously identified. After experimentally simulating natural subarctic conditions during warmer and colder months (13 and 6°C), a statistical approach identifying changes in the tendency of cercarial activity loss and mortality data was used to detect differences in three trematode genera, represented by four taxa (Diplostomum spp., Apatemon spp., small- and large-sized Plagiorchis spp.). A strong temperature-dependent response was identified in both activity loss and mortality in all taxa, with Diplostomum spp. cercariae showing the most gradual changes compared to other taxa. Furthermore, whilst activity loss and mortality dynamics could not be divided into ‘fish- vs invertebrate-infecting cercariae’ groups, the detected taxa-specific responses in relation to life-history traits indicate the swimming behaviour of cercariae and energy allocation among larvae individuals as the main drivers. Cercariae exploit the short transmission window that allows a stable continuance of trematodes’ life cycles in high-latitude freshwater ecosystems.
尾蚴的活动和存活是吸虫传播的关键特征。温度尤其重要，因为在高温下，有限的尾蚴能量储备会更快耗尽。高纬度地区的季节性气候条件可能难以在长达 6 个月的无冰期内完成吸虫的生命周期，但温度对淡水尾蚴的活动和存活的影响以前尚未确定。在实验模拟温暖和寒冷月份（13°C 和 6°C）的自然亚北极条件后，使用一种统计方法识别尾蚴活动损失和死亡率数据的趋势变化，以检测四个分类群（双腔吸虫属、单殖吸虫属、小型和大型片形吸虫属）的三种吸虫属的差异。在所有分类群中，尾蚴的活动损失和死亡率都表现出强烈的温度依赖性反应，与其他分类群相比，双腔吸虫属尾蚴的变化最为缓慢。此外，虽然无法将活动损失和死亡率动态分为“鱼类感染性尾蚴和无脊椎动物感染性尾蚴”组，但与生活史特征相关的检测到的分类群特异性反应表明，尾蚴的游泳行为和幼虫个体之间的能量分配是主要驱动力。尾蚴利用短暂的传播窗口，使高纬度淡水生态系统中的吸虫生命周期得以稳定延续。
