Selbach Christian, Marchant Loïc, Mouritsen Kim N
Department of Biology, Aquatic Biology, Aarhus University, Aarhus, Denmark.
Centre for Water and Environmental Research, University of Duisburg-Essen, Essen, Germany.
R Soc Open Sci. 2022 Jan 26;9(1):211774. doi: 10.1098/rsos.211774. eCollection 2022 Jan.
Fear plays a crucial role in predator-prey interactions and can have cascading impacts on the structure of whole ecosystems. Comparable fear effects have recently been described for hosts and their parasites but our understanding of the underlying mechanisms remains limited by the lack of empirical examples. Here, we experimentally tested if bivalves can potentially 'learn to fear' the infective transmission stages (cercariae) of the trematode , and if experienced mussels change their parasite-avoidance behaviour accordingly. Our results show that previous experience with parasites, but not established infections, lead to a reduced filtration activity in mussels in the presence of cercariae compared to parasite-naive conspecifics. This reduction in filtration activity resulted in lower infection rates in mussels. Since parasite avoidance comes at the cost of lower feeding rates, mussels likely benefit from the ability to adjust their defence behaviour when infection risks are high. Overall, these dynamic processes of avoidance behaviour can be expected to play a significant role in regulating the bivalves' ecosystem engineering function in coastal habitats.
恐惧在捕食者与猎物的相互作用中起着至关重要的作用，并且可能对整个生态系统的结构产生连锁影响。最近，类似的恐惧效应也在宿主及其寄生虫之间被描述，但由于缺乏实证例子，我们对其潜在机制的理解仍然有限。在此，我们通过实验测试双壳贝类是否有可能“学会恐惧”吸虫的感染传播阶段（尾蚴），以及有过经历的贻贝是否会相应地改变其避免寄生虫的行为。我们的结果表明，与未接触过寄生虫的同种个体相比，之前接触过寄生虫（而非已建立感染）会导致贻贝在有尾蚴存在时过滤活动降低。这种过滤活动的降低导致贻贝的感染率降低。由于避免寄生虫是以较低的摄食率为代价的，贻贝在感染风险较高时可能会从调整其防御行为的能力中受益。总体而言，这些避免行为的动态过程预计将在调节双壳贝类在沿海栖息地的生态系统工程功能中发挥重要作用。
