Physiological and Behavioural Interactions Between Parasites and Invertebrate Hosts

Abstract

This chapter focuses on the host–parasite interactions that provide new insights into the biochemistry, physiology, ethology, and ecology of the respective partners. This is, particularly, so in the case of parasitic infections of invertebrates for the following reasons: (i) the short generation time and large population size of many invertebrate hosts make them convenient models for study, and the need to understand the role of invertebrate vectors in the transmission cycles of parasitic disease is of particular relevance; and (ii) invertebrates are utilized by a variety of protozoan and helminth parasites as definitive or intermediate hosts in complex life cycles, some of which involve vertebrates. Using examples of parasitic protozoans, helminths, crustaceans, and insects in association with a wide range of invertebrate hosts, strategies, such as the synchronization of host–parasite life cycles, alteration of host growth rates, the impairment of host reproductive capacities, parasite establishment in hosts of different sexes, and alterations in host behavior are examined. A parasitic association succeeds only if the host survives long enough to enable the parasite to complete the particular phase of its life cycle and if the host population is able to persist in time. The mode and degree of integration of a variety of invertebrates and their parasites are also examined.