Which of the following is considered a mechanical/physical control measure?

Mechanical or physical control measures refer to methods that use physical barriers or manipulations to prevent pests from causing harm to crops, animals, or human health. Building barriers is a quintessential example of this type of control because it involves using tangible objects or structures to block or deter pest access. This could include physical structures like fences, nets, or walls that prevent pests from entering a specific area.

On the other hand, pesticide application involves chemical control, which is not a mechanical method. Crop rotation is a cultural control strategy aimed at disrupting pest life cycles and enhancing soil health rather than employing physical barriers. Releasing natural predators relies on biological control, which introduces other organisms to manage pest populations rather than using physical means to block them.

Thus, building barriers effectively exemplifies a mechanical or physical control measure because it relies on direct physical means to manage pest intrusion.