Infectious disease remains a major health problem and as recent epidemics emphasise may have a
major economic impact in agriculture. Furthermore the risk of emergence of infectious disease is
increasingly recognised as a global health threat. In the natural world there is also an increasing
awareness that disease plays an important role in the structuring of natural communities, the
population dynamics of their hosts and the conservation of endangered species. There is
therefore considerable research effort focussed on understanding and managing disease. Central
to this understanding of infectious disease is a better understanding of the evolutionary dynamics
that drive the characteristics of the disease interaction. It is clearly important to understand the
factors that determine the virulence (mortality) that infectious disease agents cause. In addition it
is critical to understand the processes that maintain diversity in both the disease agent and their
hosts. This diversity plays a key role in determining disease spread and is fundamental to the
potential for evolution of the disease. Ecological feedbacks and the environment may play an
important role in determining both the degree of virulence that evolves and the potential for
diversification. I use mathematical/computer models and laboratory based insect model systems
to examine how ecology influences the evolution of infectious disease. Here I will give two
examples of this work. Firstly I will show how ecological feedbacks can generate diversity in hosts
and parasites. Next I will show how variation in spatial structure and contact networks within host
populations can have important implications to the evolution of disease virulence. The approach is
to combine mathematical models with more general computer simulations and use an insect virus
system to test the assumptions and the predictions of the models.