ABSTRACT

Crop loss can be defined as the measurable reduction in quantity or quality of yield.1 Quantifying the relationship between pest numbers and damage and crop loss is a vital component needed for the development of decision making rules in integrated pest management (IPM) programs. Optimal control decisions cannot be made without reliable crop loss estimates.1 The economic injury level (EIL) is the basis of economic decision making in pest management and is defined as the lowest number of insects that will cause economic damage, which is the amount of injury that will justify the cost of control.2 Economic damage is determined by the integration of control costs, commodity market value, and damage per insect. Damage per insect often is further divided into injury per insect and damage per unit of injury.2 Injury focuses on the pest and is the effect of pest activity (usually feeding) on host physiology, whereas damage is the measurable crop loss as a result of plant response to pest injury. Control costs and commodity values are easily determined for most control measures and commodities, but quantifying the relationship between damage and insect numbers requires expensive detailed studies under representative field conditions. Achieving representative conditions often requires experiments at more than one location and in more than one year. This chapter reviews experimental approaches for quantifying the relationships between insect numbers or populations and crop yield loss.