Which of the following is a biological control method used in IPM?

The introduction of natural predators is a biological control method utilized in Integrated Pest Management (IPM) because it involves using organisms that naturally prey on pest species to reduce their populations. This method is an environmentally friendly approach, aiming to maintain ecological balance and minimize the need for chemical interventions. For instance, ladybugs are often introduced to control aphid populations, effectively reducing pest numbers through natural predation.

In contrast, the other approaches listed focus on different strategies that do not fall under biological control. Disruption of pest habitats can hinder pest development and reproduction but does not employ biological agents. The application of chemical pesticides involves synthetic substances designed to kill pests, which can have broader ecological impacts and may lead to pest resistance. The use of synthetic repellents prevents pests from approaching crops but also does not rely on the natural control of pest populations. Therefore, introducing natural predators aligns most closely with the principles of biological control in IPM.