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.