Аннотация:Both theoretical and empirical evidence suggest that infectious disease can be a major determinant of the dynamics of host populations and, more broadly, of the species composition of plant and animal communities. Previous studies of host-parasite systems have, for the most part, laid emphasis on epidemiological interpretations of the host-parasite interactions. In this article, we extend previous models of multiparasite systems and relate these models to general concepts of predator-prey and competitive interactions. In particular, we explore in some detail three different roles that parasites may play: (1) a predator or true parasite of healthy hosts, (2) an intraguild predator of a competing parasite, and (3) a competitor with a second parasite species or strain. Our analyses uncover a varied and diverse array of outcomes, in terms of both species composition and ensuing population dynamics. It is found that the two parasites are most likely to persist when there are trade-offs in exploitative (e.g., transmission) and interference (e.g., cross-transmission) competition. Regulation of the host population occurs when both parasites act as true parasites (i.e., infected hosts may recover and/or give birth to healthy hosts), whereas when one parasite acts as a predator (or pathogen) persistent oscillations may ensue. Additional realistic modifications of the models considered should greatly increase our knowledge about host-parasite systems
