Parasites as prey: the effect of cercarial density and alternative prey on consumption of cercariae by four non-host species

Welsh, Jennifer E.; Liddell, Caroline; Meer, Jaap van der; Thieltges, David W.

doi:10.1017/s0031182017001056

Cited by 28 publications

(19 citation statements)

References 40 publications

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“…The loss of cercariae by consumption from different organisms has been reported (e.g. rotifers, molluscs, insect larvae, fishes; Orlofske et al 2015 ; Welsh et al 2017 ), but its importance appears to be largely overlooked despite the significant contribution parasites may have to energy flow through food webs when being consumed by non-host organisms (Thieltges et al 2008 ; Johnson et al 2010 ). Cercarial consumption may also be context dependent, influenced by environmental conditions such as temperature or habitat complexity, in addition to the impact of the size and behaviour of the parasite and the predator (e.g.…”

Section: Introductionmentioning

confidence: 99%

Temperature does not influence functional response of amphipods consuming different trematode prey

et al. 2020

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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.

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Section: Introductionmentioning

confidence: 99%

Temperature does not influence functional response of amphipods consuming different trematode prey

et al. 2020

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“…The variety of non-host organisms causing the reductions is not only limited to active predators but also includes passive predators such as filter feeders and organisms creating physical barriers between the parasite and its host 16,21 . Thus, non-host organisms are known to affect parasite transmission in macro parasite-host systems, a phenomenon known as transmission interference 17,[22][23][24] . In this study, we used various ecologically relevant non-host organisms to assess their effects on transmission interference on a microparasite-host system.…”

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confidence: 99%

Marine virus predation by non-host organisms

Welsh

Steenhuis

Moraes

et al. 2020

Sci Rep

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Viruses are the most abundant biological entities in marine environments, however, despite its potential ecological implications, little is known about virus removal by ambient non-host organisms. Here, we examined the effects of a variety of non-host organisms on the removal of viruses. The marine algal virus PgV-07T (infective to Phaeocystis globosa) can be discriminated from bacteriophages using flow cytometry, facilitating its use as a representative model system. Of all the non-host organisms tested, anemones, polychaete larvae, sea squirts, crabs, cockles, oysters and sponges significantly reduced viral abundance. The latter four species reduced viral abundance the most, by 90, 43, 12 and 98% over 24 h, respectively. Breadcrumb sponges instantly removed viruses at high rates (176 mL h −1 g tissue dry wt −1) which continued over an extended period of time. the variety of non-host organisms capable of reducing viral abundance highlights that viral loss by ambient organisms is an overlooked avenue of viral ecology. Moreover, our finding that temperate sponges have the huge potential for constant and effective removal of viruses from the water column demonstrates that natural viral loss has, thus far, been underestimated.

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“…Direct consumption of free-living parasite stages, such as cercariae, by predators is a possibility in many systems and has been shown to play a significant role in shaping parasite transmission success (e.g. Welsh et al , 2017). However, we were able to exclude the possibility of predation on cercariae within the paralysed group, as they were incapable of movement.…”

Section: Resultsmentioning

confidence: 99%

Do behavioural defence mechanisms explain different levels of trematode infections in congeneric hosts?

2018

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Susceptibility and tolerance to parasite infection vary greatly between host species. The congeneric isopod species Austridotea annectens and Austridotea lacustris often occur in sympatry and can both serve as intermediate hosts for the trematode Maritrema poulini. However, the intensity and prevalence of infections vary greatly in natural populations, with A. annectens often being heavily infected and A. lacustris rarely being infected. To shed light on the factors that may be involved in infection avoidance in A. lacustris, 100 isopods were collected and experimentally exposed to M. poulini cercariae. To examine for potential behavioural mechanisms, we used carbonated water as a paralysing agent to temporarily stop any movement by the isopods, and exposed paralysed isopods to cercariae. In the experiments, none of the individuals that were exposed to the parasite were found to be infected, although some cercariae seemed to have penetrated isopod hosts. Behavioural defence mechanisms do not seem to explain the different infection levels between A. lacustris and A. annectens, suggesting a physiological, possibly immunological, factor may be present. At the ecosystem level, this suggests a potential dilution effect caused by this low-competency host, and its effects on parasite transmission dynamics should be investigated.

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Parasites as prey: the effect of cercarial density and alternative prey on consumption of cercariae by four non-host species

Abstract: suggest that cercarial predation effects on disease risks will depend on the specific species 32 composition of ambient communities and not on non-host biodiversity per se.

Cited by 28 publications

References 40 publications

Temperature does not influence functional response of amphipods consuming different trematode prey

Temperature does not influence functional response of amphipods consuming different trematode prey

Marine virus predation by non-host organisms

Do behavioural defence mechanisms explain different levels of trematode infections in congeneric hosts?

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