Consumer and host body size effects on the removal of trematode cercariae by ambient communities

Welsh, Jennifer E.; Hempel, Anke; Markovic, Mirjana; Meer, Jaap van der; Thieltges, David W.

doi:10.1017/s0031182018001488

Cited by 9 publications

(12 citation statements)

References 42 publications

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“…Hopper et al [37] indicate that not all co-occurring non-host species are of equal importance, even within representatives of one feeding functional group. This point of view supports Welsh et al [61] who suggest that parasite removal rates by predators are species specific, while Selbach et al [38] emphasize that the use of cercariae as prey is highly dependent on the interspecific interaction between their dispersion behaviour and the feeding behaviour of predators. However, other factors influencing cercarial consumption have not been taken into account, such as diluter density or initial density of cercariae [21,53].…”

Section: Discussionsupporting

confidence: 66%

Invaders as Diluents of the Cercarial Dermatitis Etiological Agent

et al. 2021

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Research on alien and invasive species focuses on the direct effects of invasion on native ecosystems, and the possible positive effects of their presence are most often overlooked. Our aim was to check the suitability of selected alien species (the snail Physa acuta, the bivalve Dreissena polymorpha, and the gammarid Dikerogammarus villosus) as diluents for infectious bird schistosome cercariae—the etiological factor of swimmer’s itch. It has been hypothesized that alien species with different feeding habits (scrapers, filterers and predators) that cohabit the aquatic environment with intermediate hosts of the schistosomatid trematodes are capable of feeding on their free-swimming stages—cercariae. In the laboratory conditions used, all experimental animals diluted the cercariae of bird schistosome. The most effective diluents were P. acuta and D. villosus. However, a wide discrepancy in the dilution of the cercariae between replicates was found for gammarids. The obtained results confirm the hypothesis that increased biodiversity, even when alien species are involved, creates the dilution effect of the free-living stages of parasites. Determining the best diluent for bird schistosome cercariae could greatly assist in the development of current bathing areas protection measures against swimmer’s itch.

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Section: Discussionsupporting

confidence: 66%

Invaders as Diluents of the Cercarial Dermatitis Etiological Agent

et al. 2021

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“…The greater vulnerability to predation has been attributed to the dispersion strategy and much larger body of Trichobilharzia sp. “peregra” cercariae, as also documented for other predator–prey–parasite interactions (e.g., [ 67 , 68 , 69 , 70 ]). Therefore, generating an alternative phenotype, which may benefit from owning a large body potentially facilitating transmission of cercariae, can be at the same time substantially mitigated.…”

Section: Discussionsupporting

confidence: 52%

Somatic Dimorphism in Cercariae of a Bird Schistosome

et al. 2022

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Phenotypic polymorphism is a commonly observed phenomenon in nature, but extremely rare in free-living stages of parasites. We describe a unique case of somatic polymorphism in conspecific cercariae of the bird schistosome Trichobilharzia sp. “peregra”, in which two morphs, conspicuously different in their size, were released from a single Radix balthica snail. A detailed morphometric analysis that included multiple morphological parameters taken from 105 live and formalin-fixed cercariae isolated from several naturally infected snails provided reliable evidence for a division of all cercariae into two size groups that contained either large or small individuals. Large morph (total body length of 1368 and 1339 μm for live and formalin-fixed samples, respectively) differed significantly nearly in all morphological characteristics compared to small cercariae (total body length of 976 and 898 μm for live and formalin samples, respectively), regardless of the fixation method. Furthermore, we observed that small individuals represent the normal/commonly occurring phenotype in snail populations. The probable causes and consequences of generating an alternative, much larger phenotype in the parasite infrapopulation are discussed in the context of transmission ecology as possible benefits and disadvantages facilitating or preventing the successful completion of the life cycle.

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“…Potential consumers of cercariae encompass a variety of non‐host organisms including fish, insect larvae, rotifers, bivalves or arthropods (e.g. Kaplan et al., 2009; Orlofske et al., 2015; Welsh et al., 2014, 2019), in which consumption does not lead to successful parasite transmission (Johnson et al., 2010; Thieltges et al., 2013).…”

Section: Introductionmentioning

confidence: 99%

Cercarial behaviour alters the consumer functional response of three‐spined sticklebacks

Born-Torrijos

Paterson

Beest

et al. 2021

Journal of Animal Ecology

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Free‐living parasite life stages may contribute substantially to ecosystem biomass and thus represent a significant source of energy flow when consumed by non‐host organisms. However, ambient temperature and the predator's own infection status may modulate consumption rates towards parasite prey. We investigated the combined effects of temperature and predator infection status on the consumer functional response of three‐spined sticklebacks towards the free‐living cercariae stages of two common freshwater trematode parasites (Plagiorchis spp., Trichobilharzia franki). Our results revealed genera‐specific functional responses and consumption rates towards each parasite prey: Type II for Plagiorchis spp. and Type III for T. franki, with an overall higher consumption rate on T. franki. Elevated temperature (13°C) increased the consumption rate on Plagiorchis spp. prey for sticklebacks with mild cestode infections (<5% fish body weight) only. High consumption of cercarial prey by sticklebacks may impact parasite population dynamics by severely reducing or even functionally eliminating free‐living parasite life stages from the environment. This supports the potential role of fish as biocontrol agents for cercariae with similar dispersion strategies, in instances where functional response relationships have been established. Our study demonstrates how parasite consumption by non‐host organisms may be shaped by traits inherent to parasite transmission and dispersal, and emphasises the need to consider free‐living parasite life stages as integral energy resources in aquatic food webs.

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Consumer and host body size effects on the removal of trematode cercariae by ambient communities

Cited by 9 publications

References 42 publications

Invaders as Diluents of the Cercarial Dermatitis Etiological Agent

Invaders as Diluents of the Cercarial Dermatitis Etiological Agent

Somatic Dimorphism in Cercariae of a Bird Schistosome

Cercarial behaviour alters the consumer functional response of three‐spined sticklebacks

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