The method that can be classified as a biological control for pests is the release of natural predators. Biological control involves using living organisms to manage pest populations, which can include predators, parasitoids, or pathogens that target specific pests. When natural predators are introduced into an environment, they can help maintain pest populations at levels that do not cause significant harm to crops or the ecosystem. This method is often sustainable and can reduce the reliance on chemical pesticides, contributing to more environmentally friendly pest management strategies.
In contrast, the application of pesticides is a chemical control method that involves the use of synthetic or natural chemicals to kill or deter pests. Crop rotation is an agronomic practice that disrupts pest life cycles and can help reduce pest populations but is not classified as a biological control method. Similarly, the use of plastic barriers is a physical control method aimed at preventing pests from reaching plants, not utilizing biological agents to control pest populations.