Guild structure of larval trematodes in molluscan hosts: prevalence, dominance and significance of competition

Abstract

Descriptive analyses of parasite community structure are now available for a wide variety of vertebrate hosts (see Chapters 1, 5, 6, 7, 8 and 9; see also Choe and Kim, 1987). Parasite communities of invertebrate hosts have received less attention. Yet, important features distinguish invertebrates as hosts for parasites. These attributes may impart some unique characteristics to the structure or organization of parasite communities of invertebrate hosts in contrast to vertebrate hosts. Firstly, invertebrates are usually smaller than vertebrates. Secondly, many invertebrates, particularly arthropods and molluscs, serve as intermediate hosts for parasites that complete their development in a vertebrate host. These multiple host life cycles considerably complicate the nature of parasite community organization. Consequently events in the vertebrate hosts, remote in space and time, may play a direct role in the structure of parasite communities of invertebrate intermediate hosts. The reverse is also possible; dynamics in the invertebrate host may affect parasite community structure in the vertebrate hosts. Further, invertebrate populations are generally more amenable to experimentation and field manipulation than are vertebrates. Thus, the organizational features of parasite communities in invertebrate hosts may be studied using the most powerful methodologies available to community ecologists (Castilla and Paine, 1987).