Learn about biological control of Agricultural pests—how natural predators, parasitoids, and pathogens help manage pests sustainably. Discover its methods, benefits, and limitations.
Biological Control of Agricultural Pests: Definition, Methods, and Benefits
Introduction
Pest control is essential in agriculture to ensure healthy crop yields and reduce post-harvest losses. While chemical pesticides have been widely used, their overuse can harm the environment, beneficial organisms, and human health. An eco-friendly alternative is the biological control of agricultural pests, which involves using living organisms to suppress pest populations naturally.
In this hall, we are going to be learning the concept of biological control, the types of natural enemies used, methods of application, and its benefits and limitations.
READ ALSO – Types of Agricultural Pests and their Effects with Examples
What is Biological Control?
Biological control (or biocontrol) refers to the use of natural enemies—such as predators, parasites, or pathogens—to control the population of harmful pests in agriculture. These natural enemies help reduce pest numbers without harming the crops or environment.
Types of Biological Control Agents
1. Predators
Predators are organisms that feed directly on pests.
Examples:
- Lady beetles eat aphids.
- Spiders prey on caterpillars and flies.
- Lacewings consume whiteflies and thrips.
2. Parasitoids
Parasitoids are insects that lay their eggs on or in a host insect. When the eggs hatch, the larvae feed on the host, eventually killing it.
Examples:
- Parasitic wasps (e.g., Trichogramma) attack caterpillar eggs.
- Tachinid flies parasitize beetles and moths.
3. Pathogens
These are disease-causing organisms such as bacteria, fungi, or viruses that infect and kill pests.
Examples:
- Bacillus thuringiensis (Bt) bacteria control caterpillars.
- Entomopathogenic fungi infect and kill grasshoppers or aphids.
- Nuclear polyhedrosis viruses (NPVs) affect caterpillar pests.
Methods of Biological Control of Agricultural Pests
1. Classical Biological Control
This involves the introduction of a natural enemy from the pest’s native region to a new area where the pest has become a problem.
- Example: Introducing parasitic wasps to control mealybugs in Africa.
2. Augmentative Biological Control
This involves the mass rearing and release of natural enemies to boost their population and effectiveness.
- Example: Releasing large numbers of Trichogramma wasps into maize fields.
3. Conservation Biological Control
This focuses on protecting and enhancing the population of existing natural enemies in the environment.
- Example: Avoiding chemical pesticides that harm beneficial insects.
- Growing flowering plants to attract pollinators and predators.
Benefits of Biological Control of Agricultural Pests
- Environmentally Friendly: Reduces chemical pesticide use.
- Target-Specific: Affects only the target pest without harming beneficial organisms.
- Cost-Effective: Once established, natural enemies can control pests over the long term.
- Sustainable: Supports long-term pest management and biodiversity.
- Safe for Humans and Animals: No toxic residues on crops or in the environment.
Limitations of Biological Control
- Takes Time: Effects may not be immediate like chemical pesticides.
- Specific Conditions Needed: Some agents need certain temperatures, humidity, or prey densities to thrive.
- Risk of Imbalance: Introducing foreign species can sometimes affect local ecosystems.
- Requires Monitoring: Regular observation is needed to assess effectiveness.
Examples of Biological Control in Nigeria and Beyond
- Use of Bacillus thuringiensis to control armyworms in maize.
- Introduction of Aphidius colemani wasps to control aphids in vegetable farming.
- Release of predatory mites to manage spider mites in tomato and pepper farms.
Revision Questions and Answers
1. What is biological control in agriculture?
Answer:
Biological control is the use of natural enemies—such as predators, parasitoids, or pathogens—to manage and reduce populations of agricultural pests.
2. Mention three types of biological control agents and give one example of each.
Answer:
- Predators – Example: Lady beetles that eat aphids.
- Parasitoids – Example: Parasitic wasps like Trichogramma.
- Pathogens – Example: Bacillus thuringiensis (Bt) bacteria used to control caterpillars.
3. What are the three main methods of applying biological control?
Answer:
- Classical biological control – Introducing natural enemies from another region.
- Augmentative biological control – Mass production and release of natural enemies.
- Conservation biological control – Protecting and enhancing existing natural enemies.
4. List four benefits of biological control of agricultural pests.
Answer:
- Environmentally friendly and non-toxic.
- Reduces use of chemical pesticides.
- Promotes long-term pest control.
- Encourages biodiversity and soil health.
5. What are two major limitations of biological control?
Answer:
- It may take time for results to show.
- It requires technical knowledge and monitoring.
6. Why is biological control of agricultural pests important for organic farming?
Answer:
Because it offers a natural, chemical-free way to manage pests, making it ideal for systems where synthetic pesticides are restricted or banned.
Conclusion Biological Control of Agricultural Pests
Biological control is a natural and sustainable way to manage agricultural pests. By using predators, parasitoids, and pathogens, farmers can protect their crops while safeguarding the environment and human health. Though it requires planning and patience, biological control is a long-term solution that fits well with modern integrated pest management strategies.