CLASS NOTE: PESTS IN AGRICULTURE

Subject: Agricultural Science Class: JSS 1 Topic: Pests: Definition and Types of Pests Curriculum: Nigeria National Curriculum (NERDC)

---

1. COMPREHENSIVE CORE CONCEPTS

What is a Pest?

In the world of agriculture, not every living thing on a farm is a friend to the farmer. A pest is any organism (living thing) that causes physical damage, economic loss, or disease to our crops, livestock, and even our stored food.

Think of a pest as an "unwanted guest" that competes with humans for food. For instance, if you plant a beautiful garden of fluted pumpkin (Ugu), and a goat comes to eat the leaves before you can harvest them, that goat is acting as a pest. However, in agriculture, we specifically focus on organisms like insects, rodents, and birds that habitually destroy farm produce. A pest is defined not just by what it is, but by the harm it does.

Why Do We Study Pests?

Understanding pests is crucial for food security in Nigeria. When pests attack our farms, they reduce the amount of food available in the market, which makes food prices go up. By studying them, we learn their habits, how they feed, and the best ways to stop them without harming the environment.

Classification of Pests

Pests are generally grouped into three main categories to help farmers identify and manage them effectively:

A. Based on the Type of Organism

1. Insects: These are the most common pests. They have six legs and bodies divided into three parts. Examples include grasshoppers, locusts, aphids, and weevils.
2. Rodents: These are mammals with sharp front teeth for gnawing. Examples include rats, mice, and squirrels. They are notorious for digging up newly planted seeds or eating stored grains.
3. Birds: Certain birds, like weaver birds, descend on rice or maize farms in large numbers and eat the ripening seeds.
4. Other Animals: This includes snails, monkeys, and even certain types of crabs in riverine farming areas.

B. Based on Feeding Habits (Mouthparts)

This is one of the most important ways to identify pests because the damage they leave behind tells us who the "thief" is:

• Biting and Chewing Pests: These pests have strong mandibles (jaws) to bite off and swallow pieces of plants. You will see holes in leaves or ragged edges.
  • Examples: Grasshoppers, Termites, and Caterpillars.
• Piercing and Sucking Pests: These pests have a needle-like mouth (proboscis). They pierce the plant tissue and suck out the liquid sap, causing the plant to wilt, turn yellow, or become stunted.
  • Examples: Aphids, Cotton stainers, and Whiteflies.
• Boring Pests: These pests (often larvae/grubs) eat their way into the stems, fruits, or seeds of a plant. They live inside the plant while eating it.
  • Examples: Maize stalk borer and Bean weevils.

C. Based on Habitat (Where they are found)

• Field Pests: These attack crops while they are still growing on the farm. (e.g., Grasshoppers on cassava).
• Storage Pests: These attack crops after they have been harvested and kept in granaries, silos, or the kitchen. (e.g., Weevils in beans).

---

2. REAL-WORLD EXAMPLES (SCENARIOS)

• Scenario A: The "Disappearing" Bean Seeds Imagine your mother buys a bag of beans from the local market and keeps it in the store. A month later, she opens the bag and finds tiny holes in the beans and a lot of "dust" at the bottom. This is the work of the Bean Weevil (a storage pest).

• Scenario B: The Wilted Tomatoes A student starts a small tomato garden behind the house. One morning, the leaves look curled and yellowish, but there are no holes in them. Upon closer inspection, tiny green insects are found under the leaves. These are Aphids (piercing and sucking pests) draining the plant’s "blood" (sap).

• Scenario C: The Midnight Thief A farmer plants yam. At night, Rats (rodents) dig into the soil and eat the newly formed tubers. The farmer only realizes this when the yam vines start dying because the roots and tubers have been eaten.

---

3. PRACTICAL APPLICATIONS: HOW TO IDENTIFY PEST DAMAGE

If you want to be a "Plant Doctor," follow these steps to identify what type of pest is attacking a plant:

1. Inspect the Leaves:
   • Holes or missing chunks? Look for Biting and Chewing insects like caterpillars.
   • Yellow, curled, or "dry" looking leaves? Look for Piercing and Sucking pests like aphids.
2. Check for "Frass" (Pest Poop):
   • Small black or brown pellets on the leaves often indicate that a caterpillar is nearby.
3. Look for Exit Holes:
   • If you see tiny holes in a fruit (like a mango or tomato) or a grain of corn, a Borer has been inside.
4. Check the Roots/Base:
   • If a plant falls over easily, a Rodent or Termite might be eating the roots underground.

---

4. PROJECT-BASED LEARNING: "THE PEST DETECTIVE DIARY"

Objective: To observe and document pests in your local environment. Materials Needed: A small notebook, a pen, a magnifying glass (optional), and a camera (optional).

Step-by-Step Instructions:

1. Identify a Site: Choose a small area like your backyard, a nearby garden, or the school farm.
2. Observation: Visit the site for 3 days. Look at different plants (leaves, stems, and fruits).
3. Documentation: In your notebook, create a table with these headings:
   • Date
   • Plant Name (e.g., Maize, Hibiscus)
   • Type of Damage Seen (e.g., holes in leaves, yellowing)
   • Pest Sighted (e.g., "I saw a green grasshopper")
   • Pest Classification (e.g., Biting and Chewing)
4. Conclusion: At the end of the 3 days, write a short summary of which type of pest was most common in your area.

---

5. HOME PRACTICE ACTIVITY: THE GRAIN PROTECTION EXPERIMENT

Goal: To understand how storage pests (weevils) work and how to prevent them. Materials:

• Two small transparent glass or plastic jars.
• A handful of dried beans or maize.
• A piece of cloth and a rubber band.

Procedure:

1. Divide the beans into two equal portions.
2. Jar A (Protected): Put the beans in the jar and seal it tightly with its lid.
3. Jar B (Unprotected): Put the beans in the jar and leave it open or cover it loosely with a cloth that has holes.
4. Place both jars in a dark corner of the kitchen for 2 weeks.
5. Observation: After 2 weeks, check for the presence of weevils or holes in the beans.
6. Expected Outcome: Jar B is more likely to show signs of pest activity because it was easily accessible.

---

6. LIFE SKILLS INTEGRATION: BEYOND THE FARM

• Critical Thinking: Learning to identify pests helps you solve problems by looking at "symptoms" before suggesting a "cure." This is the same logic used by doctors and engineers.
• Resource Management: In your home, knowing about storage pests helps you save money by storing food properly (using airtight containers), preventing "food waste."
• Career Connections:
  • Entomologists: Scientists who study insects to help protect crops.
  • Public Health Officers: Use pest knowledge to control mosquitoes (which are pests to humans) and rats in cities.
  • Agro-Entrepreneurs: Successful farmers must be experts in pest management to ensure they make a profit.

---

7. STUDENT REFLECTION QUESTIONS

1. If you find a pest with no wings but very strong hind legs and large jaws, what type of feeding habit do you think it has, and where would you likely find it?
2. Why is it that a goat can be a "pet" in the house but a "pest" on a vegetable farm?
3. In your own kitchen at home, which food items are most "at risk" of being attacked by storage pests? List three ways you can protect them.
4. If all pests in the world were suddenly destroyed, do you think it would be good for the environment? (Hint: Think about birds that eat insects).
5. How does the presence of pests in Nigeria affect the price of a bag of rice at the local market?