Non-host organisms impact transmission at two different life stages in a marine parasite
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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.
KeywordsBiodiversity Cercariae Dilution effect Metacercariae Philophthalmus sp. Predation Transmission success
CS was supported financially by a postdoctoral fellowship from the German Research Foundation (DFG, SE 2728/1-1).
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Conflict of interest
The authors declare that they have no conflict of interest.
- Jones MB, Marsden ID (2005) Life in the estuary: illustrated guide and ecology. Canterbury University Press, ChristchurchGoogle Scholar
- Mironova E, Gopko M, Pasternak A, Mikheev V, Taskinen J (2018) Trematode cercariae as prey for zooplankton: effect on fitness traits of predators. Parasitology. https://doi.org/10.1017/S0031182018000963
- Thieltges DW, Bordalo MD, Caballero-Hernandez A, Prinz K, Jensen KT (2008a) Ambient fauna impairs parasite transmission in a marine parasite-host system. Parasitology 135:1111–1116Google Scholar
- Thieltges DW, Jensen KT, Poulin R (2008b) The role of biotic factors in the transmission of free-living endohelminth stages. Parasitology 135:407–426Google Scholar
- Thieltges DW, Amundsen P-A, Hechinger RF, Johnson PTJ, Lafferty KD, Mouritsen KN, Preston DL, Reise K, Zander CD, Poulin R (2013) Parasites as prey in aquatic food webs: implications for predator infection and parasite transmission. Oikos 122:1473–1482Google Scholar