Frequently, we assume that the relationship between parasites and hosts is similar to that between predators and their prey, where one party (the prey or host) tries to avoid any form of interaction with the other (the predator or the parasite): the former will lose fitness (in the worst case, by dying), whilst the latter will gain fitness from the interaction.
However, for many parasite-host systems, the relationship isn’t that simple. Once a host has the fortune of being parasitised, it may pay for it to alter its behaviour and physiology to tolerate the parasite (if mounting an immune defence is costlier than simply putting up with the parasite), or at least make the best of the reduction it suffers to its fitness. Similarly, a parasite may need to remain in the host for a long period of time, and antagonising the host further could lead to a reduction in the resources the host is able to provide, or maybe even the death of the host at an inappropriate moment (which could be catastrophic to a parasite that relies on the host for its own survival).
This suggests that the behaviour of both the host and the parasite will dynamically change in response to the requirements of the other, which means that we can use approaches used in other fields of behavioural ecology for exploring these interactions. Work (in collaboration with Andrew Fenton at the University of Liverpool) has so far explored how state-dependent foraging theory can be used to explore parasitoid infection strategies, and how parasite manipulation of host behaviour may affect population biology.
The Royal Society has also funded some exploratory work considering how state-dependent dynamic game theory can be used to explore the moment-to-moment behavioural rules used by interacting hosts and parasites. This work is currently being brought together into a manuscript – please contact Sean if you’re interested in knowing a little more.
Fenton A & Rands SA (2006). The impact of parasite manipulation and predator foraging behavior on the structure of predator-prey communities. Ecology 87: 2832-2841 | abstract
Fenton A & Rands SA (2004). Optimal parasite infection strategies: a state-dependent approach. International Journal for Parasitology 34: 813-821 | abstract
Rands SA (2012). Mobbing and sitting tight at the nest as methods of avoiding brood parasites. Interface Focus 2: 217-225 | abstract
If you’re interested in knowing more about parasite ecology, why not join the British Ecological Society’s special interest group in parasite and pathogen ecology and evolution?