Parasitology Research

, Volume 118, Issue 1, pp 111–117 | Cite as

Non-host organisms impact transmission at two different life stages in a marine parasite

  • Sofia Vielma
  • Clément Lagrue
  • Robert Poulin
  • Christian SelbachEmail author
Original Paper


The potential for local biodiversity to ‘dilute’ infection risk has been shown to be particularly important in aquatic trematodes, where non-host organisms can feed on free-living infective stages (cercariae) and reduce transmission rates to target hosts. Non-host organisms could also impact transmission during other stages of the trematode life cycle. In Philophthalmus spp., cercariae encyst as metacercariae on external surfaces, where they remain exposed to the adverse effects of non-host organisms. In laboratory experiments, we tested the potential for a range of non-host organisms to (i) prey on cercariae, (ii) induce early (i.e., faster) encystment and (iii) prey on or destroy metacercariae. Our results show that intertidal anemones, and to a lesser extent clams, can consume substantial numbers of cercariae. However, we found no strong evidence that the presence of these predators causes cercariae to encyst faster as a way to escape from predation. We also found that grazing snails can reduce numbers of encysted metacercariae, either by eating or crushing them. Our findings add to the growing evidence that trematode transmission success can be strongly affected by the local diversity of non-host organisms. They also reinforce the notion that parasites are potentially important food items for many organisms, thus playing roles other than consumers in many food webs.


Biodiversity Cercariae Dilution effect Metacercariae Philophthalmus sp. Predation Transmission success 


Funding information

CS was supported financially by a postdoctoral fellowship from the German Research Foundation (DFG, SE 2728/1-1).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Institute of Biology, Faculty of SciencesUniversity of PécsPécsHungary
  2. 2.Department of Biological SciencesUniversity of AlbertaEdmontonCanada
  3. 3.Department of ZoologyUniversity of OtagoDunedinNew Zealand

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