The multitrophic level approach to ecology addresses the complexity of food webs much more realistically than the traditional focus on simple systems and interactions. Only in the last few decades have ecologists become interested in the nature of more complex systems including tritrophic interactions between plants, herbivores and natural enemies. Plants may directly influence the behaviour of their herbivores' natural enemies, ecological interactions between two species are often indirectly mediated by a third species, landscape structure directly affects local tritrophic interactions and below-ground food webs are vital to above-ground organisms. The relative importance of top-down effects (control by predators) and bottom-up effects (control by resources) must also be determined. These interactions are explored in this exciting volume by expert researchers from a variety of ecological fields. This book provides a much-needed synthesis of multitrophic level interactions and serves as a guide for future research for ecologists of all descriptions.