Date: 6^th-17^th of February 2023

Class: SSS 2

Term: 2^nd Term

Week: 5&6

Subject: Agricultural Science

Topic: Pests of crops

Duration:45 minutes

Teaching Aid: A chart

Reference Book: 1. Essential Agricultural Science for Senior Secondary Schools by O.A Iwena(page241-243)

Comprehensive Certificate Agricultural Science For Senior Secondary Schools by L.A Are et al (page340-346)

Behavioural Objectives: By the end of this topic, students should be able to

Define pests
Mention the types of crop pests and classify insect pests
Discuss prevention of pests

Presentation

Step 1: Teacher revises last topics

Step 2: Teacher introduces and explains new topic

Step 3: Teacher dictates note

Step 4: Teacher evaluates students

Step 5: Teacher marks students' notes and give assignment

Previous knowledge: Students have been taught Pasture and forage

Content

MEANING OF CROP PEST

A pest can be described as any organism capable of causing damage to crop plant.

Types of Crop Pest.

Important pests of crop plants are grouped into the following classes:

(i) insect; (ii) birds; (iii) rodents; (iv) monkeys; (v) man; (vi) nematodes

CLASSIFICATION OF INSECT PESTS

Insects pests can be classified into various groups based on their mode of feeding. These groups of insect pest include:

Bitting and chewing insects;
Piercing and sucking insects;
Boring insects.
Biting and Chewing Insects: These insect (mouth-parts) which enable them to bite and chew plant parts. Examples include: termites, grasshoppers, leaf worms, army worms, mantids, locust, beetles, etc.
Piercing and sucking insects: These insect pests posses strong mouthparts called proboscis stuck liquid from materials from plants’ tissues. Examples include aphids, cotton strainers, mealy bugs, scale insects, capsids or mirids, white flies, etc.
Burrowing insects: These insects including their larvae are capable of burrowing into plant parts and destroying the tissues of the plant or fruits or seeds. Examples include: bean beetles, stem burrowers, maize weevils and rice weevils.

IMPORTANT PEST OF MAJOR CROPS

Insect Pest	Crops Attacked	Nature of Damage and Economic Importance	Prevention and Control Measure
Stem burrower	Cereals e.g. rice, maize, guinea corn	i. Larvae bore holes into stems. ii. They eat up the plant iii. They weaken the plant iv. Reduced growth and yield	i. Uproot and burn infected plant. ii. Spray with insecticides e.g. Gammlin 20. iii. Early planting iv. Crop rotation.
Army Worm	Cereals e.g. maize	i. Larvae invade and eat up leaves and stem ii. Reduce photosynthesis iii. Retarded growth iv. Reduced yield	i. Hand picking ii. Spray with insecticides e.g. DDT.
Pod Burrower	Legumes e.g. cowpea, soyabeans	i. Larvae bore into the pod. ii. They eat up the seeds. iii. Reduced yield iv. Introduce disease	i. Crop rotation ii. Early harvesting iii. Spray with insecticides
Aphids	Legumes e.g cowpea, soyabeans	i. Stunted growth ii. Galls on leaves iii. Vectors of disease e.g. rosette, mosaic disease of cowpea	i. Spray with insecticides to kill vector ii. Uproot and burn infected plant
Leaf beetle	Legume e.g. cowpea soyabeans	i. They eat up the leaves ii. Reduce photosynthesis iii. Reduced yield	i. Spray with insecticides ii. Use resistant varieties
Cocoa mirids (capsids)	Beverages e.g. cocoa	i. They inject toxic saliva into plant ii. Transmit fungal diseases iii. Reduced yield iv. Stunted growth	i. Spray with insecticide e.g. Gammalin 20 ii. Regular weeding
Yam beetles	Tubers e.g. yam	i. Bore holes into yam tubers ii. Reduction in yield iii. Reduction in quality and market value	i. Dust yam sets with Adrin dust before planting ii. Crop rotation
Cassava mealybugs	Tubers e.g. cassava	i. Twisting of stem and reduce internodes ii. Swelling of shoots iii. Reduced yield	i. Early planting ii. Use resistant varieties iii. Cutting treatment iv. Spray with insecticides
Green spidermite	Tuber e.g. cassava	i. They feed on the leaves ii. Reduce rate of photo synthesis iii. Reduction in yield	i. Use biological control ii. Spray with insecticides.
Variegated grasshopper	Tubers e.g. cassava, yam	i. Adults and larvae eat up the leaves and stem ii. Reduce the rate of photosynthesis iii. Reduced growth iv. Reduced yield	i. Hand picking ii. Spray with insecticides e.g. Adrex 40.
Cotton stainer	Cotton	i. They pierce and suck sap from plants. ii. Produce toxic saliva iii. Transmit diseases. iv. Reduce quality of boll v. Leaf distortion	i. Hand picking ii. Spray with insecticides.
Cotton bollworm	Cotton	i. Larvae feed on the seeds of cotton ii. Crop rotation iii. Destroy the lint and reduce its quality iv. Premature fall of cotton boll.	i. Spray with insecticides to kill insects. ii. Burn cotton plant debris after harvesting.
Thrips	Vegetables e.g. onion, tomato	i. Browning of leaves ii. Wilting of plant iii. Reduced yield	i. Spray with insecticides.
Leaf rollers Leaf beetle	Vegetable Vegetables e.g. pepper, okro, tomato	i. Rolling and twisting of leaves. ii. Reduction in rate of photosynthesis. iii. Reduce yield iv. They eat up the leaves and stems v. Reduced photosynthesis vi. Reduction in yield and quality	Spray with insecticides e.g. Vetox 85. Spray with appropriate insecticides e.g. Vetox 85
Bean beetle, grain weevils	Stored produce e.g. rice, cowpea, maize	i. Bore holes into grainsand eat them up. ii. Reduce the quality of stored produce iii. Reduce quality of grains to powder iv. Reduce farmer’s income v. It reduces the market value of grains vi. It reduces viability of infested grains.	i. Early harvesting ii. Proper storage of produce iii. Proper cleaning and fumigation of store with phostoxin tablets or with lindane dust iv. Store grains over fire places v. Proper drying of seeds to reduce moisture content and kill the eggs and larva of pest.
Birds	Rice, maize, millets, sorghum	i. Feed on grains in the field ii. Reduction in quality and yield iii. Reduction in income of farmer	i. Use of bird scarer or scare cow. ii. Use of cage traps with baits iii. Drumming or noise making on the farm iv. Shooting with catapult v. Use of explosive mechanism at regular intervals vi. Use of avicides vii. Fencing/screening farms in greenhouse.
Rodents e.g. bush rabbit, rats, squirrel	Rice, yam, cassava, fruits	i. They feed on crops ii. Destroy whole plants iii. Reduction in yield iv. Increase in cost of production	i. Trapping with baits ii. Use of rodenticides iii. Use of string/wire tapes iv. Use of predator e.g. dogs and cats v. Clean weeding of farms vi. Shooting and fencing vii. Use of pit traps.
Monkeys	Cocoa, mango, banana, orange.	i. They eat up the fruits ii. Reduce the quality of fruits iii. Losses to the farmer	i. Use traps ii. Shooting with gun where possible

EFFECTS OR ECONOMIC IMPORTANCE OF INSECT PESTS IN CROP PRODUCTION

Insects pest destroy crops in the field through their biting, chewing, boring, sucking and defoliation activities
They cause reduction in viability of stored produce
Spot of injuries by insets may predispose crops to disease attact.
They increase the cost of production during the course of controlling them
They render vegetables and fruits unattractive and unmarketable
Some are carriers or vectors of diseases.
The profits of farmers are reduced
They reduce the quality of produce either in the store or in the field
They generally reduce the yield of crops
They can also cause total death of crop plants.

PREVENTION AND CONTROL OF PESTS.

Pests of crops can be prevented or controlled through the following methods:

(1) Physical control; (2) Cultural Control (3) Biological control; (4) chemical control.

Physical Control: This involves the physical removal of pests by:
Handpicking of insects and larvae,
Setting traps to catch rodents.
Shooting rodents with gun.
Fencing round the farm with wire nets.
Cultural Control: This method involves the use of farm practise to prevent or control pest especially on the field. Examples of cultural control include:
Practicing crop rotation
Use of pest resistant varieties of crops

Appropriate tillage operations

Use of insect traps
Handpicking and destruction of insects,
Burning crop residues,
Timely planting of crops
Proper weeding or sanitation
Timely harvesting.
Close season practices, especially in cotton

Biological Control: This involves the introduction of the natural enemies of pest to control or the pests population under control. Such enemies eat up or feed on these pests thereby reducing the population of the pest.
Chemical Control: This involves the use of chemical called insecticides or pesticides to control pests or crop plants.

Definition of Insecticides

An insecticide is a chemical preparation used to control insect pest.

Forms of Groups of Insecticides

There are four major forms or groups of insecticides used in the control of insect pests of crops. These forms or groups and their mode of action are:

Groups mode of action

(i) Powder (i) Contact

(ii) Liquid (ii) Systemic

(iii) Granules (iii) Stomach

(iv) Gas (eous) (iv) Fumigation

These groups of insecticides can be used either directly on insects, seeds, plants and plant parts to check the activities of insects.

Examples of chemicals used to control pests are:

Pesticides - chemicals to control pests
Insecticides - chemicals to control insect, e.g. Grasshopper
Rodenticides - Chemicals to control rodents, e.g. Rats
Avicides - Chemicals to control birds, e.g. weaver birds
Nematicides - Chemicals to control nematodes, e.g. Eel worms.

SIDE EFFECTS OF THE VARIOUS PREVENTIVE AND CONTROL METHODS OF DISEASE AND PESTS OF CROPS

The use of various control methods of disease and pests has some side effect. These side effect are follows:

(a) Chemical Method of Control

Some beneficial insects and soil organisms may be destroyed
The chemical used may be toxic to man and domestic animals

It may leave undesirable residue in the environment

Pests and diseases may develop resistance to chemicals
Some are washed out of soil to rivers and streams where they can endanger aquatic life and cause pollution
Empty containers could be a source of poisoning when used as container for consumables.

(b) Biological Methods of Control

The new organism introduced may start attacking crops which were originally free from attack
The predators expected to control other may rather feed on other beneficial insects

The activities of the new organism introduced may cause serious imbalance in the ecosystem.

(c) Cultural Method of Control:

The use of fire to kill harmful pests may also result in the destruction of other beneficial organism
Resistant varieties may become adapted to the environment so that the resistance in short-lived where fire is used.

It care is not taken, fire may spread to other farms.

The use of fire may cause the destruction and loss of organic matter from the soil
It may also lead to the destruction of soil structure and cause soil erosion.

Evaluation: describe the classes of insect pests

Assignment: draw one insect pests in each classes(alternative to practical)

Lesson Notes By Weeks and Term - Senior Secondary School 2