Which condition is necessary for a compound to be considered a pest?

A compound is considered a pest primarily when it causes economic harm. This is rooted in the definition of a pest, which often centers around the impact on agriculture, property, and health. Pests can lead to financial losses through damage to crops, structures, and even products, directly affecting livelihoods and industries. For example, a species that damages crops can lead to reduced yields and increased costs for farmers, thereby fulfilling the definition of a pest based on economic impact.

While non-native species (the second option), rapid reproduction (the third option), and potential harm to human health (the fourth option) can be characteristic traits of certain pests, they do not universally define what constitutes a pest. A species may be native and still be harmful or non-harmful regardless of its reproduction rate. Therefore, the defining characteristic is its ability to cause economic harm, making this condition essential for classifying a compound as a pest.