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Term: 2nd Term
Class: Senior Secondary School 2
Age: 16 years
Duration: 40 minutes of 2 periods each
Topic:- Pest of crops
SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to
INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source
INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures
The teacher reviews the previous lesson on crop diseases
Students pay attention
She explains the meaning of crop pests
She states the types of crop pests
Students pay attention and participates
She discusses the classes of crop pests and the damages caused by them
She further discusses the effects of crop pests on crop production
Students pay attention and participate
The teacher writes a summarized note on the board
The students copy the note in their books
A pest can be described as any organism capable of causing damage to crop plant.
Types of Crop Pest.
CLASSIFICATION OF INSECT PESTS
Insects pests can be classified into various groups based on their mode of feeding. These groups of insect pest include:
DAMAGES CAUSED BY PESTS
They feed by biting pieces of plant material and chewing. It may be adult or larvae of insects.
The type of damage done by them may be generalized as follows:
(a) Loss of photosynthetic tissues; in extreme cases defoliation may result.
(b) Destruction of buds and shoots.
(c) Destruction of flowers, fruits and seeds.
(d) Boring and tunnelling of stems; interruption of sap flow and physical weakening of the stem; stem breakage may result.
(e) Eating or boring of roots and tubers in the soil.
(f) Destruction of seedlings and young plants.
(g) Formation of galls on all or any parts of the plant body.
These pests have part or all of the mouthparts modified into a piercing proboscis or stylet. Sap is sucked either from the phloem or xylem or from general tissues of foliage, roots or fruits. Within this category there are two basically different types of damage.
(a) Pests without toxic saliva:
These insects and mites remove sap, causing tissue wilt, leaf curl, stunting and in extreme condition causes death of the host plant.
(b) Pests with toxic saliva:
In this case toxic saliva causes a disproportionate amount of damage in relation to insect number. The toxins cause death of the cells and if injected into a young shoot, the entire shoot, distal to the feeding site, may die.
These pests are extremely harmful, as a very small number of infective individuals may be responsible for severe outbreak of disease. Disease control by destruction of vectors is very difficult.
These pests are of two types:
(a) Indirect vectors:
This category includes those insects that make feeding punctures, which later becomes infected by aerial spores; this occurs in fruits, tunnelled by fruit fly larvae (Tephritidae) and fruit worms (Lepidoptera).
(b) Direct vectors:
These insects and nematodes are sometimes called ‘biological vectors’. They are responsible for active transmission, as they are often intermediate hosts. The pathogens are plant microbes, which can only be transmitted through vectors
PREVENTION/CONTROL OF CROP PESTS
METHODS OF PEST CONTROL
Crop pests can be prevented or controlled through the following methods:
This involves the physical removal of pests by:
This method involves the use of farm practices to prevent or control pests, examples of cultural control are:
This involves the introduction of natural enemies of pests to control or keep the pest population under control. Such enemies eat up or feed on these pests, thereby reduce the population of the pests.
This involves the use of chemical called pesticides to control pest of crop plants. Examples of pesticides are insecticide, rodenticide, avicide etc.
Examples of chemicals used to control pests are:
EVALUATION: 1. Explain the meaning of crop pests
CLASSWORK: As in evaluation
CONCLUSION: The teacher commends the students positively