Which statement about action threshold is true?

The statement that the action threshold for a pest may be set at a zero pest population density is true because it highlights a strategic approach in pest management. An action threshold is a predetermined level of pest population at which management actions should be taken to prevent unacceptable damage to crops or the environment. Setting this threshold at zero indicates a highly proactive stance where any appearance of the pest triggers an immediate response. This approach is particularly relevant in scenarios where a pest poses a significant risk to the health of the crop or ecosystem, emphasizing the importance of early intervention.

In practical terms, while action thresholds are often set based on economic, ecological, or health-related considerations, a zero threshold tends to be adopted in situations where the presence of a pest could lead to severe consequences, such as in dedicated organic or high-value crops where standards for pest presence may be extremely stringent. By recognizing the action threshold at zero, managers can limit the development of pest populations effectively.