This is the fourth volume of a series devoted to providing a comprehensive review of the study of plant-eating insects, covering topics ranging from biochemistry to ecology and evolution. Volume IV examines the status of mutualism, using the fig-insect interaction; phytosterols as important components of adaptive syndromes in herbivorous insects; methods utilized by plant-eating insects to detect compounds that deter feeding, including the various codes and how and why they vary; and the nature and significance of extrafloral nectaries in plants. The book also covers the varied roles of quinolizidines in plants, in addition to reviewing the controversial arena of plant stress and insect performance. Insect-Plant Interactions, Volume IV, is an important reference work for entomologists, zoologists, ecologists, and other scientists involved in studies with insect-plant interactions.