In agriculture and pest management, biological control specifically refers to checking the growth or population of what, using another living organism?

Introduction / Context:
Biological control is an important strategy in modern agriculture and integrated pest management. Instead of relying solely on chemical pesticides, farmers and environmental managers can use natural enemies of pests to reduce their numbers. This method is more environmentally friendly and can help maintain ecological balance. This question asks what exactly is being controlled in biological control and how.

Given Data / Assumptions:

• The term used is biological control.
• We are dealing with agriculture and pest management situations.
• Options include plants, animals, weeds, one pest by another, and beneficial insects.
• We assume standard definitions used in ecology and crop protection.

Concept / Approach:
Biological control refers to the use of natural predators, parasites, or pathogens to control harmful organisms, especially insect pests, weeds, or plant pathogens. The key idea is that one living organism is used to limit the population of another problematic organism. Classic examples include using ladybird beetles to control aphids and introducing specific parasitoid wasps to manage caterpillar pests. The focus of the definition is on reducing populations of pests by their natural enemies. It is not primarily about controlling general plant growth, beneficial animals, or beneficial insects.

Step-by-Step Solution:
Step 1: Recognise that in agricultural science, pests are organisms that damage crops, stored products, or livestock. Step 2: Understand that biological control aims to reduce these pest populations without heavy use of synthetic chemicals. Step 3: In biological control, farmers introduce or encourage natural enemies such as predators, parasites, or disease causing organisms that specifically attack the pests. Step 4: Therefore, biological control is essentially controlling one pest species by another living organism, usually its natural enemy. Step 5: The concept does not focus on directly controlling plants or beneficial animals, although weeds and plant diseases are sometimes addressed by similar methods. Step 6: Thus, among the options given, the most accurate description is checking the growth of one pest species by another living organism.

Verification / Alternative check:
Ecology and agricultural textbooks define biological control as the use of one organism to control another, typically pests such as insects, mites, weeds, and plant pathogens. They cite examples like the introduction of the Cactoblastis moth to control prickly pear cactus in Australia and use of Bacillus thuringiensis (Bt) bacteria to control caterpillar pests. These descriptions emphasise that biological control is about using living agents against pests.

Why Other Options Are Wrong:
Plants: Biological control does not mainly aim at controlling plant growth; it aims at controlling pest organisms that damage plants. Animals: While pests may be animals, the option is too broad and does not capture the idea of one pest being controlled by another organism. Weeds: Weeds can be targets of biological control, but the definition is not limited to plants; it is about pests in general. Beneficial insects: These are often the agents used in biological control, not the targets whose growth is checked.

Common Pitfalls:
Students sometimes think biological control only refers to controlling weeds or only to using insects. The concept is broader and includes pests of many kinds and various natural enemies. To answer correctly, focus on the idea that one living organism is used to control another harmful one, which is best captured by the option describing one pest species being controlled by another living organism.

Final Answer:
The correct answer is One pest species by another living organism.