Economic Injury Level refers to the pest density at which the cost of pest damage equals the cost of control.

• A. The pest density at which the cost of pest damage equals the cost of control
• B. The pest density at which management action should be taken to prevent reaching the Economic Threshold
• C. The pest density at which crop yield becomes unprofitable
• D. The pest density at which beneficial insects start to decline

Answer: (A)

The main idea being tested is balancing costs: the economic injury level is the pest density where the expected damage from pests equals the cost of taking control actions. At that point, applying control just pays for itself; below it, damages cost less than control, so action isn’t yet economical, and above it, the losses from pest damage would exceed control costs, making management worthwhile. This concept helps growers decide when control is financially justified.

Remember the distinction from the economic threshold: that threshold is the pest density at which you should begin action to prevent reaching the economic injury level, essentially a proactive cue to stay ahead. The option about yield becoming unprofitable is a related idea but not the precise definition—EIL specifically ties damage cost to control cost. The idea about beneficial insects declining isn’t related to this economic decision point.