The action threshold for a pest may be set at zero pest population density.

• A. True
• B. False
• C. Not sure
• D. It depends

Answer: (A)

The main idea is that action thresholds are management triggers for when to start control to keep pest levels from causing economic damage. While many thresholds are set at a specific density above zero, there are situations where zero pests is chosen as the trigger. This happens in high-value crops or confined environments like greenhouses or nurseries, where even a single pest can quickly establish, spread, or transmit disease, leading to significant losses. In such cases, any detectable pest justifies action, so the threshold is set at zero. This approach prioritizes preventing damage entirely, even if it means more frequent interventions.