What is an economic threshold for grasshoppers in rangeland and why is it important?

• A. The pest density at which the damage costs exceed the control costs
• B. The pest density at which the cost of damage equals the cost of control
• C. When pest numbers reach zero
• D. A fixed density regardless of crop value

Answer: (B)

An economic threshold is the pest density at which taking action becomes financially justified because the expected cost of the damage from the pests equals the cost of the control measure. For grasshoppers in rangeland, this threshold tells you when to intervene so that you prevent losses from rising faster than the cost of treatment.

This is important because acting too early wastes money and can cause unnecessary environmental impact, while waiting too long lets damage accumulate and can exceed what control costs would have prevented. By aiming to act at the point where damage costs equal control costs, you’re timing management to be economically effective and to keep forage losses from spiraling. The other options describe scenarios that don’t reflect the trigger for cost-effective action: waiting until damage already costs more than control is past the optimal point, a zero pest level isn’t realistic for triggering action, and a fixed density regardless of value ignores how forage value and pest dynamics drive economic decisions.