This book brings together scientists from diverse disciplines to discuss the potential effectiveness of metabolites derived from microorganisms, higher plants, and insects. It looks at structure-function relationships for naturally occurring cyclic peptides. Covering the production of herbicidal and insecticidal metabolites by soil microorganisms, this volume discusses biological activities of fungal products and phenol gluocosides in plant defense against herbivores. It includes chapters on allelopathy as a model for natural herbicide actions and terpenoids as models for new agrochemicals. It examines plant constitutents as oviposition deterrents to lepidopterous insects and pentatomoid sex pheromones.