Disease in group-defending prey can benefit predators

Infectious diseases have the capacity not only to influence the host population but also interacting species like predators. In particular, they can reduce host densities, which can have knock-on effect on predators. In this talk, we consider how an infectious disease in the prey affects the predator--prey relationship when the prey exhibit some kind of group defence against the predator. We find that the disease can reduce prey densities to levels where the group defence is weaker. This weakened group defence allows predators to survive in many scenarios where they could not without the disease.