Parasites as predators: unifying natural enemy ecology

Parasitism and predation have long been considered analogous interactions. Yet by and large, ecologists continue to study parasite–host and predator–prey ecology separately. Here we discuss strengths and shortcomings of the parasite-as-predator analogy and its potential to provide new insights into both fields. Developments in predator–prey ecology, such as temporal risk allocation and associational resistance, can drive new hypotheses for parasite–host systems. Concepts developed in parasite–host ecology, such as threshold host densities and phylodynamics, might provide new ideas for predator–prey ecology. Topics such as trait-mediated indirect effects and enemy-mediated facilitation provide opportunities for the two fields to work together. We suggest that greater unification of predator–prey and parasite–host ecology would foster advances in both fields.