Which is a non-chemical control method in pest management?

Biological control using natural predators is considered a non-chemical control method because it involves leveraging the natural ecosystem to manage pest populations. This strategy relies on the introduction or encouragement of natural enemies, such as predatory insects, parasites, or pathogens, which can help keep pest populations in check without the use of synthetic chemicals. By using these natural solutions, pest management can be achieved in an environmentally friendly manner, promoting ecological balance and reducing the reliance on chemical inputs.

The other methods listed involve chemical interventions. Soil fumigation introduces gases or vapors that eliminate pests and pathogens, insecticide application involves the use of chemical pesticides specifically designed to kill or repel pests, and the use of chemical repellents uses synthetic substances to deter pests. These options rely on chemical inputs, which can have side effects on non-target species and the environment, contrasting with the biological approach that seeks to utilize existing natural processes.