In contrast to books on specific bioactive compounds, this book deals with the role of mevalonic acid metabolites (isoprenoids and their derived structures) in metabolism, development, and functions of organisms, which, though diverse, show various levels of communication. Different disciplines are brought together in a discussion of the messenger functions of terpenoids within and between organisms belonging to five biological kingdoms: bacteria, fungi, plants, insects, and vertebrates (including humans). The present volume covers evolutionary aspects of terpenoids in plant physiology, plant–insect relationships, semiochemicals, and in life sciences, with special emphasis on cancer research and treatment. The book provides proposals for multidisciplinary model systems for the study of interrelationships of organisms utilizing terpenoid messengers, and discusses novel strategies for insect control and multifactor treatments of cancer utilizing terpenoids. This book is of interest to scientists, and students at an advanced level: biologists, plant breeders, pharmacologists, specialists in medical fields, especially oncologists, physicians in general, and anyone with a basic biochemical and physiological knowledge.