Trophic and Guild Interactions and the Influence of Multiple Species on Disease.

Most studies of host-parasite systems consider the interaction between one host and one parasite species. The aim of this chapter is to illustrate how the presence of other interacting species can influence the outcome of particular host-pathogen/parasite interactions. We begin with a brief review of the disease literature considering three broad categories of interactions: (i) cases with one pathogen/parasite and multiple shared hosts; (ii) cases with one host and multiple shared pathogens and/or parasites; (iii) cases with generally one host and pathogen but considering the influence of other interacting species such as natural enemies or competitors. We then consider some specific examples drawn from investigations into the use of fungal entomopathogens for biological control of locusts and grasshoppers. These case histories serve to highlight how an understanding of more complex trophic or guild interactions could help in improving the safety and effectiveness of biological control using pathogens. [ABSTRACT FROM AUTHOR]