Education Always

Level: JHS, Basic 9  |  Subject: Integrated Science  |  Strand: Cycles  |  Topic: Life Cycle of Crop Pests and Integrated Pest Management

Curriculum reference: B9.2.2.1 Understand the life cycle and economic impact of crop pests. Indicator B9.2.2.1.1: Describe the life cycle of common agricultural pests (e.g., stem borers or weevils). All the exemplars are merged into one set of notes.

1. What Is a Pest?

A pest is any living thing that damages crops, stored food or farm animals and so reduces yield or profit. Common crop pests are insects (stem borers, weevils, armyworms, aphids), rodents (rats), birds (weaver birds) and nematodes.

2. Life Cycle of an Insect Pest

Many pests go through complete metamorphosis with four stages: egg, larva, pupa, adult.

Stage	What happens
Egg	The adult female lays eggs on the leaf, stem or grain
Larva	Eggs hatch into larvae (caterpillars or grubs). This is the feeding stage and does most damage.
Pupa	The larva stops feeding and changes inside a case. No feeding.
Adult	The adult comes out, mates and lays eggs, and the cycle starts again

Maize stem borer

• The adult moth lays eggs on maize leaves.
• The larvae (caterpillars) bore into the stem and feed inside.
• Damage: dead heart in young plants, broken stems, poor cobs. Yield is reduced.
• The pupa forms inside the stem or in crop residue.

Weevil (in stored maize, cowpea or rice)

• The adult beetle lays eggs on or in the grain.
• The grub feeds inside the grain and hollows it out.
• The pupa forms inside the grain, and the adult makes a small round exit hole.
• Damage: holes, weight loss, powder (flour dust), bad smell and poor germination.

Fall armyworm, a caterpillar pest that attacks maize leaves and cobs, is also common in Ghana.

3. Economic Effects of Pests

• Lower crop yield and quality.
• Food shortage and higher food prices.
• Money lost on pesticides and storage.
• Loss of income for farmers.

4. Integrated Pest Management (IPM)

IPM uses several methods together to keep pests below harmful levels, with the least damage to people and the environment.

Method	Examples
Cultural	Crop rotation, early planting, clearing crop residue, weeding, resistant varieties, intercropping
Mechanical and physical	Hand picking, traps, scarecrows, nets, sun drying grain, sealing stores
Biological	Natural enemies such as birds, spiders, wasps, ladybirds; neem seed extract
Chemical	Pesticides used only when needed, in the right dose, with protection
Legal	Quarantine rules that stop pests from entering a country

Safe storage: dry grain well, clean the store, use hermetic (airtight) bags, and use neem or wood ash.

Safe use of pesticides: read the label, wear gloves and a mask, never spray near water or food, never reuse empty containers, and wait for the stated period before harvesting.

Remember: The larva does the damage, and IPM combines methods, with chemicals as the last choice.

Education Always (education.inspiringalways.com). Original notes written to follow the NaCCA Basic 9 Integrated Science curriculum.