Natural enemy ecology: comparing the effects of predation risk, infection risk and disease on host behavior

1. Growing interest in unifying the field of natural enemy ecology has revealed similarities between predation and parasitism. In parallel with predation, parasite infection – and even the threat of infection – can alter host traits and indirectly affect community interactions. Nonetheless, few studies have considered multiple mechanisms of natural enemy-induced behavioural alteration in parallel (e.g. effects before and after enemy contact) or the factors that drive variation in behavioural responses. 2. We first evaluated how the threat of infection by a virulent trematode (Ribeiroia ondatrae) compared to the well studied risk of predation in triggering inducible defences in amphibian hosts, prior to direct contact with either enemy. We then evaluated five separate factors that influenced the magnitude of parasite-induced behavioural changes after successful transmission. 3. In both the laboratory and an outdoor mesocosm experiment, we found no evidence that tadpoles of two species (P...