Biotic Stress and Yield Loss

PrefaceThe idea for this book came to us after we organized a symposium at the 1996 meetingof the North Central Branch of the Entomological Society of America. The symposiumwas titled Understanding Yield Loss from Insects and its focus was on currentknowledge of insect herbivores and their impact on plant fitness and yield loss. Whenwe discussed the idea, we recognized it would be important to cover all biotic stressors(insects, plant pathogens, and weeds) because it is critical to compare and contrastplant responses to all biotic stressors if we are ever going to develop moreencompassing understandings of plant stress. The participation of writers from manyareas was essential for this project, and we are greatly appreciative of the contributionsfrom our authors for this volume. We also appreciate and thank MarijeanPeterson for her editorial reviews and assistance in manuscript preparation.This book is a natural extension of a previous volume, Economic Thresholds forIntegrated Pest Management, edited by Higley and Pedigo. Where that book focusedon economic decision levels and pest management for insects, plant pathogens, andweeds, this book concentrates on plant physiological, developmental, growth, andyield responses to biotic stress. Most of the chapters discuss biotic stress primarilywithin an agricultural context. This largely reflects the current state of knowledge forplants and biotic stress. Much more is known about biotic injury and agriculturalcrops than biotic injury and wild plants within ecosystems. Many of the chapters alsodiscuss plant response and yield loss to insect herbivores. This is partly a reflectionof our backgrounds and disciplinary bias, but is also a reflection of the relative richnessof entomological research efforts to characterize plant responses to insect injury.This is not to imply that our understandings of biotic stress and plant responseare adequate. To our knowledge, this is the first book to cover the topic of biotic stressand yield loss. Although one type of biotic stress—arthropod injury—may be betterunderstood than the others, plant responses to biotic stresses continue to be largelyignored and poorly understood. Indeed, the term plant stress has been synonymouswith the abiotic stresses—temperature, moisture, and mineral nutrition stress. Weneed to elevate our knowledge of biotic stress to the same level as abiotic stress if weare to meaningfully comprehend biotic stress and integrate both abiotic and bioticstress into a general understanding of plant stress.One theme that emerges from many chapters in this volume is the need to regardstress as a general phenomenon affecting plants. Although there are profound differencesbetween plants grown in agroecosystems and natural ecosystems, to us, one ofthe most appealing features of focusing on biotic stress is the potential for greaterintegration of plant ecophysiology. Many authors have recognized the schismbetween work on biotic stress in the basic and applied sciences (research on herbivoryoffers one striking example). As discussions in this book point out, it is timeto look for commonalities and exploit the advantages offered by work in both sys-vii