Do different parasite species interact in their effects on host fitness? A case study on parasites of the amphipodParacalliope fluviatilis

Abstract

There is a gap in our understanding of the relative and interactive effects of different parasite species on the same host population. Here we examine the effects of the acanthocephalan Acanthocephalus galaxii, an unidentified cyclophyllidean cestode, and the trematodes Coitocaecum parvum and Microphallus sp. on several fitness components of the amphipod Paracalliope fluviatilis, using a combination of infection surveys and both survival and behavioural trials. In addition to significant relationships between specific parasites and measures of amphipod survival, maturity, mating success and behaviour, interactions between parasite species with respect to amphipod photophilia were also significant. While infection by either A. galaxii or C. parvum was associated with increased photophilia, such increases were negated by co-infection with Microphallus sp. We hypothesize that this is due to the more subtle manipulative effect of A. galaxii and C. parvum being impaired by Microphallus sp. We conclude that the low frequency at which such double infections occur in our sampled population means that such interactions are unlikely to be important beyond the scale of the host individual. Whether or not this is generally true, implying that parasitological models and theory based on single parasite species studies do generally hold, requires cross-species meta-analytical studies.

Lessons in Mind Control: Trends in Research on the Molecular Mechanisms behind Parasite-Host Behavioral Manipulation

“…When infected gammarids are disturbed they display photophilic behaviors, actively swimming toward the surface and clinging to debris. The opposite behavior is exhibited in their uninfected counterparts, which swim down into the benthic layer Holmes, 1973, 1974;Rauque et al, 2011). This behavioral manipulation of infected gammarid's makes them more susceptible to avian predators, increasing trophic transmission opportunities for the parasite (Bethel and Holmes, 1977).…”

Spatial covariation of local abundance among different parasite species: the effect of shared hosts

“…Not only are spatial patterns of matching and mismatching densities among parasite species important drivers of coevolutionary dynamics (see Thompson 2005), but they also determine the extent and frequency at which host populations suffer from additive or synergistic effects of multiple infections (e.g. Ferguson and Stiling 1996;Rauque et al 2011). The findings of the present study suggest that a basic comparison of life cycle requirements may provide a simple predictive framework, an insight that will require further empirical validation from other systems.…”

Cooperation and conflict in host manipulation: interactions among macro-parasites and micro-organisms

“…Fourth, it has been suggested that given the relatively low frequency of manipulative parasites, co-occurrence is generally a very rare event in the field. Consequently, such a weak selection pressure should have no important consequences beyond the host individual level (Rauque et al, 2011). However, this might not be a correct way of reasoning.…”

“…For instance, using naturally infected individuals, Rauque et al (2011) found that co-infection with the trematode Microphallus sp. impaired the ability of both the acanthocephalan Acanthocephalus galaxii and a cyclophyllidan cestode to alter the phototaxis of the amphipod Paracalliope fluviatilis .…”