Which type of pesticide is defined as a substance to directly control pest populations?

The term that encompasses all substances used to control pests is "pesticide." Pesticides can be classified into various categories based on the type of pest they target, but the general definition includes any chemical or biological agent that is intended to kill, repel, or mitigate pest organisms. This broad category covers insecticides (which target insects), herbicides (which target unwanted plants or weeds), and fungicides (which control fungal issues). Each of these specific types operates under the umbrella of 'pesticide' as they all serve the purpose of pest control. Therefore, recognizing that "pesticide" is the overarching classification is essential in understanding how these substances are utilized in managing pest populations effectively.