Biology

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New Senior School Biology Practical Activity & Work Book Two

Chapter

PEST AND DISEASES
OF CROPS

Notable Concepts

What is a pest?
Classification of pest
Life cycle of pest
Control of pest

* * * * * * * * * * * * *

fig8.1 Rice weevil: An insect pest

Background Information

What is a pest? A pest is any organism (plant, animal, fungi, virus etc) which is injurious or harmful to cultivated plants and their products. Plant pests are called weeds.Examples of pests are

Insects: such as aphids, grasshoppers, caterpillar etcMammals such as rats, rabbits, bats, fox etc

Classification of pests

Pests can be classified using certain basis1. The part of the plant they attack. For example: stem borers, leaf feeders , young short feeders, root feeders and seed feeders

2. We can also classify pests based on the organism type. Here we have plant pests and animal pests. Also under animal pests we can classify further to

Invertebrates pests example insects, nematodes etc

Vertebrate pests which include birds such as pigeon, weaver, bird etc

Mammals such as rats, rabbits, monkeys, bats etc.

Mode of feeding	Pests	Effects	Crops, their activities affect	Control measures
Boring and chewing	Maize Weavil
Boring and chewing	Bean Weavil	Eats and damages stored beans	Beans	Fumigation and use of insecticide

fig8.2 beetle an insect pest

fig8.3 grasshopper an insect pest

fig8.4 caterpillar an insect pest

Bird Pests

Pest	Effects	Crops, Its activity Affects	Control
Bush fowl	Decreases crop yields through its damage to crops	Corn, groundnut cassava	Use of Objects or Mechanical devices that can Make a noise
Quelea bird	Cause decreased crop yield by feeding on grains	Maize, Millet, guinea Corn, rice	Spraying with chemicals
Guinea fowl	Causes a decrease in crop yield	Groundnuts	Scaring devices and loud noise
Village Weaver bird	Damages crops (Maize, rice) and reduces crop yield	Rice, Maize	Spraying of chemicals and uses of explosives

Mammalian Pests

Pest	Effects	Crops, Its activity Affects	Control
Bat	Damages riped fruits e.g mangoes	Mango, Pawpaw	Shooting and setting traps
Bush rat	Cause crop damages and destruction	yam cassava	Weeding and clearing Vegetation within and around the farm.
Monkey	Decreases crops yield at harvest	Maize, Bananna fruit	Chasing away, shooting and setting traps
West African ground squirel	Brings losses to farmers through the eating of yam and cassava	Yam, cassava	Shooting and chasing away by man.

fig8.5 Bat a mammalian pest

fig8.6 squirrel, a mammalian pest

Diseases caused by pests and their agents

Pest not only destroy crops, they also act as disease vector to crops. In the cause of their activities, they transmit or pass on crop diseases. Causative agents of crop disease and be fungi, Bacteria or Virus

Certain crop diseases and their causasive agents are tabulated below

Crop disease	Crop involved	Causative agent	Control
Blast	Rice	Fungus	Use fungicidles and resistant Variety
Rust	Maize	Fungus	Apply resistant Variety use fungicides change planting times
Mosaic	Garden egg plant, cassava, Tobacco, pepper	Virus (Transmitted by Aphids, white flies)	Use plant resistant varieties .Destroy the disease vector
Swollen Shoot disease	Cocoa	Virus (transmitted by mealy bug)	Destroy infected plants.Destroy the vector
Rosette	Groundnut	Virus (Spread by Aphids)	Pullout infected plants, use of healthy seed.Destroy the vector with insecticides
Wilt	Cassava	Bacteria	Resistant varieties Early planting destroying infected crop, use crop rotation scheme.
Blight	Cowpea	Bacteria and Fungi	Disinfect seeds before planting.

Control of Pests

Physical Method: This involves, destroying pest by catching them through traps; burning them and uses of deterrents to scare them away
Cultural Methods: This has to do with the application of farming method or practice in reducing pests. This Method can be: Timing the farming period at a time of reduced pest activities. Use of farming method like crop rotation; Proper spacing of crops etc.
Biological Method: In this method natural enemies or predator of the pests are used to fight them.
Chemical Methods: Chemicals called Pesticides are used to destroy pest and Control their activities.
Prohibitions: Banning materials that will likely introduce Pests and diseases into a place such as country or state.
Pest Resistant Varieties: Planting Pest or disease resistant varieties of crops to reduce pest attacks and activities.
Drying: Proper drying of some crop products before storage can help to reduce their water content and make them more pest resistant. Crops such as beans and maize can be treated in this way.
Quarantine Method: This involves keeping a likely infected plant under a confirmed state waiting for the disease to be noticed and confirmed. Through this, such crop or plant can be sent back or prevented from entering another place to infect other crop.

General questions

1. Crop pest can be plants or animals, plant pest can be called

2. A crop pest which also transmits diseases among crops is known as

The diagram below shows stages in the life cycle of the beetle, use it to answer questions 3-5.

fig8.7:

3. Identify and label the pupal stage

4. What type of crop pest can you categorize the animal?

5. What part of the crop does the organism attack or feed on

6. What part of the crop do locust, grasshoppers and caterpillars usually attack by feeding on it.

7. Reproduction by unfertilized egg which can be found in Aphids is called

8. An Aphid and a locust are insect pests while a bat and bush rat are

9. A guinea fowl is a bird pest which can attack or feed on a plant like

10. A cotton stainer feeds on cotton seeds by piercing and sucking while caterpillars feed on leaves by _________ and _________

biting and chewing

cutting and grinding

sucking and cutting

11. Bean weevils eat and damage stored beans, their pest activities can be controlled by

setting traps and bush cleaning

uses of proper storage and burning

fumigation and use of insecticide

12. Black pod disease of cocoa are spread by

a bacteria

a fungus

a virus

13. Blight' of cowpea can be prevented and controlled by

washing seed and spreading it on the sun

keeping the seeds in a damp shady

Disinfecting seeds before planting

14. Swollen shoot disease and cassava mosaic are viral diseases while blast in rice is caused by

fungi

bacteria

protozoan

15. Chemicals used in pest control are called

16. Stem borers of cereal crops like maize are

Larva

pupa

imago

Use the table below to answer question 17-20
Fill in a right answer for the spaces provided in the table

17 – 20	Pests	Crops they attack	Effect
17	Mealy bug	Cassava
18	Maize weevil	Maize
19	Bush fowl	Groundnut, cassava
20		Okro

Expression Exercise

1) Differentiate between herbicides, fungicides and insecticides using table below

Herbicides	Fungicides	Insecticide
1

2) Write down five insect crop pest that attack crops through biting and chewing and five crops their activities affect

3) List four mammalian pest and two ways of controlling their destructive activities on crops.

4) State one danger of the use of pesticides by farmers

5) Write three crop diseases each that are caused by

6) Explain cultural and biological methods of controlling pests
(a) Cultural methods

(b) Biological methods

7) Explain pest resistant variety as a way of controlling pest activities on crops

Practical Activities

Take a trip (your teacher can take you down) to variety of farmlands where different crops are grown. Carry out the following activities.

1 a. Give a name tag to the farmlands you visited in alphabetical order e.g Farm A, Farm B etc.

b. Collect specimens of the crops you found in these farms and identify each of them with their names

Tabulate your report as shown in the table below:

The Farms	Various specimen of crop found
Farm A
Farm B
Farm C
Farm D
Farm E

Examine each specimen carefully to find out if any is under the attack of a crop pest

If any, identify the plants and plant parts that are under such attacks and the likely or suggested pests that are involved

2. You are provided with an infested corn seed and been seed as specimen A and B respectively

(i) Carefully examine each specimen and answer the following questions based on your Observations

What are the likely pests that are involved in the attack of each specimen

(ii) State one possible crop disease that might have infested the Specimen

(iii) What is the causative organism that is responsible for the disease you stated in (ii)

Identify the larval stage in the life history of the weevil shown below
Which stage(s) of the weevil is it destructive to cereal crops

fig8.8:

3. A. The diagram in fig 8.9 is an aphid, state the name of one crop it attacks

B. What type of metamorphosis occurs in its life cycle (i.e. Aphid life cycle)

fig8.9:

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