Pest Control – JSS1 Agricultural Science Lesson Note (Second Term)

A pest is any living organism, plant or animal, that damages cultivated crops, farm animals or humans. Examples are grasshoppers and beetles (insects), rats and monkeys (mammals) and weaver birds. Insect pests are grouped by how they feed (biting and chewing, piercing and sucking, or boring) and by where they attack (field or storage).

Behavioural objectives

By the end of the lesson, students should be able to:

1. Define a pest and give examples.
2. Name the three groups of insect pests according to their feeding habit.
3. Describe the mouth parts of biting and chewing insect pests.
4. Give examples of piercing and sucking insect pests and boring insect pests.
5. Distinguish field insect pests from storage insect pests and give examples of each.

What is a pest?

A pest is a living organism, plant or animal, that can cause damage to our cultivated crop plants, farm animals and humans. Common examples include insects like grasshoppers and beetles, mammals such as rats and monkeys, and birds such as weaver birds.

How are insect pests classified according to their feeding habit?

According to their mode of feeding, insect pests are classified into three groups:

1. Biting and chewing insect pests
2. Piercing and sucking insect pests
3. Boring insect pests

Biting and chewing insect pests

Insect pests in this group have mouth parts which are specially made for biting and chewing plants. The mouth parts consist of:

• a pair of very hard biting jaws called mandibles
• a second pair of jaws called maxillae
• a flat upper lip called the labrum
• a lower lip called the labium

The mandibles are used to bite off and chew parts of the crop, while the maxillae hold the food and push it into the mouth.

Examples of biting and chewing insect pests are crickets, grasshoppers, beetles, termites, armyworms and mantises.

Piercing and sucking insect pests

The insects in this group have mouth parts that are shaped like injection needles, called probaxix, and hena. Their mouth parts are adapted to pierce into plant parts and suck the sap and juice of plants.

Examples of piercing and sucking insects include aphids, cotton stainers, mealybugs, whiteflies and capsids.

Boring insect pests

These are insects that bore holes into plant tissues and seeds. Boring insects are also called burrowing insects. Examples are bean beetles and weevils, such as rice weevils and maize weevils.

How are insect pests classified according to their location?

Based on location, insect pests are classified into two groups:

1. Field insect pests
2. Storage insect pests

Field insect pests

These are insects that attack crop plants on the field, that is, before harvesting. Important field pests include:

• Stem borers
• Fruit and seed feeders: examples are fruit beetles, fruit flies and fruit-piercing moths.
• Root feeders: examples are yam beetles.

Storage insect pests

This group of insects attacks harvested products in the store. Examples include bean beetles and weevils, such as rice weevils and maize weevils.

Evaluation

1. What is a pest? Give three examples.
2. Name the three groups of insect pests according to their feeding habit.
3. List the four parts of the mouth of a biting and chewing insect.
4. Give two examples of piercing and sucking insect pests.
5. State the difference between field insect pests and storage insect pests.

Assignment

1. List three examples of biting and chewing insect pests and three examples of piercing and sucking insect pests.
2. Name two insect pests that attack crops both in the field and in the store, or in the store only, and say where each one attacks.