Institute of Parasitology, Biology Centre, Czech Academy of Sciences, 37005, České Budějovice, Czech Republic.
School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK.
Parasitol Res. 2020 Dec;119(12):4271-4276. doi: 10.1007/s00436-020-06859-1. Epub 2020 Aug 26.
Direct consumption on free-living cercariae stages of trematodes by non-host organisms interferes with trematode transmission and leads to reduced infections in the next suitable hosts. Consumer functional responses provide a useful tool to examine relationships between consumption rates and ecologically relevant prey densities, whilst also accounting for abiotic factors that likely influence consumption rates. We investigated how temperature influences the consumer functional response of the amphipod Gammarus lacustris towards the cercariae of three freshwater trematodes (Diplostomum, Apatemon and Trichobilharzia). Amphipods displayed different functional responses towards the parasites, with Type II responses for Diplostomum and Type I responses for Apatemon prey. Temperature did not alter the consumption rate of the amphipod predator. Trichobilharzia was likely consumed at similar proportions as Diplostomum; however, this could not be fully evaluated due to low replication. Whilst Type II responses of invertebrate predators are common to various invertebrate prey types, this is the first time a non-filter feeding predator has been shown to exhibit Type I response towards cercarial prey. The prey-specific consumption patterns of amphipods were related to cercarial distribution in the water column rather than to the size of cercariae or temperature influence. The substantial energy flow into food webs by non-host consumer organisms highlights the importance of understanding the mechanisms that modulate functional responses and direct predation in the context of parasitic organisms.
自由生活的吸虫尾蚴阶段被非宿主生物直接消耗会干扰吸虫的传播，并导致下一个合适宿主的感染减少。消费者功能反应提供了一种有用的工具来检查消耗率与生态相关的猎物密度之间的关系，同时还考虑到可能影响消耗率的非生物因素。我们研究了温度如何影响淡水三种吸虫（双腔吸虫、副口吸虫和细颈吸虫）尾蚴的淡水甲壳动物（罗氏沼虾）的消费者功能反应。甲壳动物对寄生虫表现出不同的功能反应，双腔吸虫表现出 II 型反应，副口吸虫表现出 I 型反应。温度不会改变甲壳动物捕食者的消耗率。细颈吸虫可能以与双腔吸虫相似的比例被消耗；然而，由于复制数量较少，这一点无法得到充分评估。虽然无脊椎动物捕食者的 II 型反应对于各种无脊椎动物猎物类型很常见，但这是第一次表明非滤食性捕食者对尾蚴猎物表现出 I 型反应。甲壳动物的特定猎物消耗模式与水柱中尾蚴的分布有关，而与尾蚴的大小或温度影响无关。非宿主消费者生物向食物网中输入大量能量，突出了在寄生虫生物的背景下理解调节功能反应和直接捕食的机制的重要性。
