Which of the following is a mechanical device used in pest management?

The correct choice, which identifies a mechanical device used in pest management, is traps. Traps are designed specifically to capture or kill pests through physical means rather than chemicals, making them a fundamental aspect of integrated pest management. They can be used to monitor pest populations or reduce their numbers effectively and are often chosen for their ability to be specific to the target pest, minimizing impact on non-target organisms.

In contrast, pesticide sprays, while effective for controlling pests, rely on chemical action rather than a mechanical process. Fertilizers primarily serve to provide nutrients to plants and do not directly manage pest populations. Repellents are designed to deter pests but also function through chemical means rather than mechanical intervention. Thus, traps stand out as a purely mechanical tool in the overarching strategies for pest management.