Give an example of a physical control method in pest management.

The choice of manual removal of pests or using barriers such as nets exemplifies a physical control method in pest management because it relies on tangible, mechanical means to manage pest populations. Physical control methods are focused on preventing pest access or removing pests from an area without the use of chemical treatments.

For instance, manual removal directly involves the physical action of picking pests off plants or crops, thereby reducing their numbers without the complications that can arise from chemical applications. Similarly, employing barriers like nets helps to keep pests away from vulnerable plants entirely, effectively creating a physical obstacle that prevents infestation.

Using insecticides involves chemical intervention, which does not fall under the category of physical controls. Planting resistant crop varieties represents a biological method, as it centers around enhancing the plants' natural defenses rather than using physical means. Lastly, pheromone traps utilize the biological behaviors of pests to control populations but rely on chemical signals rather than physical deterrents or removal techniques. Thus, the highlighted method stands out as a clear example of a physical control strategy in pest management.