Lesson Notes By Weeks and Term - Senior Secondary School 1
PEST AND DISEASES OF CROPS AND LIVESTOCK (Cont.)
PEST AND DISEASES OF CROPS AND LIVESTOCK (Cont.)
SUBJECT: BIOLOGY
CLASS: SS1
DATE:
TERM: 3RD TERM
REFERENCES
WEEK SIX & SEVEN
PEST AND DISEASES OF CROPS AND LIVESTOCK
CONTENT
DEFINITION
A pest is an organism which harbors disease organism(s) or causes damage to other organism(s). There are crop and livestock (animals) pests. Crop pests include insects such as grasshoppers, mealy bugs, myriads, beetles, birds and mammals (such as rodents) while livestock pests are ectoparasites such as ticks, mites and endoparasites such as liver flukes, round worms and tapeworms. They can also be plant pests known as weeds or animal pests such as insects, birds, rodents, monkeys, man or nematodes.
TYPES OF PEST
Insects pest: These are arthropods that carry diseases or cause damage to plant and animals. Examples include: tick, lice, grasshoppers, cotton stainer etc.
Non insect pest: These are vertebrates and molluscs that common cause disease to plants and animals or destroy crops. E.g rodents, worms, nematodes, monkeys etc.
GROUPS OF INSECT CROP PESTS
Stem Borers: Stem borers of cereal crops like maize are the larvae of certain moths. They lay eggs at the junctions of leaf sheaths and stem of a maize plant which hatches after a week and weakens the stem causing the maize plant to break even in slight wind.
Fruit and Seed Feeders: These include fruit-piercing moths, fruit flies, cotton strainers and certain beetles. Examples are red boil-worm and the cotton stainer. Their host plant includes tomato, millet, maize and okra.
Root Feeders: They may be insect larvae or adults. An example is the yam beetle which lives mainly in the soil. They burrow into the ground and feed on yam tubers.
Leaf Feeders: Leaves of crops are eaten by snails, leaf-feeding beetles, caterpillars of various moths and butterflies, grasshoppers and locusts.
Young Shoot Feeders: Insects like aphids and mealy bug pierce and suck juices from young shoots of crop plants. They first settle on the apex and feed on the young tissue. Many sucking pests also transmit disease-causing fungi, bacteria, and virus to the plants e.g. cassava mosaic transmitted by white flies.
Life Cycle of Some Selected Pest
Grasshopper( Zonocerus variegates)
History: Male and female mate and eggs are then fertilized internally. The female then digs a hole with her ovipositor in the soil usually near the roots of plants and lays about 40 to 100 eggs the hole. A protective material is produced to cover the eggs. After about 3 days, the eggs hatch into nymphs. A nymph resembles the adult in all respect except it is sexually immature and wingless. The nymph moults several times and hops about feeding on the shoots of plants
nearby. They begin to migrate into areas where there are cassava farms and start feeding on the cassava leaves until an adult stage is attained.
LIFE CYCLE OF A GRASSHOPPER
Effects of Grasshoppers on Cassava
Nymphs and adults feed on the leaves, shoots and barks of cassava thereby reducing cassava yield drastically as photosynthesis is seriously impaired.
Control: Spray with gammalin 20.
Cassava mealy bug (Phenacoccusmanlhot)
The female insect lays eggs without fertilization by the male. This type of reproduction is called parthenogenesis. The unfertilized eggs hatch into larvae which are wind borne or carried with cassava stem cuttings during planting because they hide in the buds of the stem. The larvae undergo three moulting stages before adult stage. One generation is completed in about twenty-two days and the adult has life span of about one hundred and forty-five days.
Effects
Control: Dip cassava cutting in 0.1% ultracide solution for one minute before planting tuber
EVALUATION
The Life Cycle of Cassava Mealy bug
Life History of Bean Weevil
Male and female adults mate and fertilized eggs are then laid in the ripening pods in the farm. The eggs hatch into larvae which enter into the bean seeds before harvesting. In the store, the larvae feed on the cotyledons of the beans. The larvae develop into pupae in the store. The pupae later develop into adults which fly away to mate again in the farm.
Effects
The larvae feed on the seed thereby reducing the quality and value of the beans.
Control
Fumigate the store in which beans are stored with fumigants such as methyl bromide.
Cocoa Myriads (Capsid)
These are piercing and sucking insects. They attach the young shoot of cocoa, introducing toxic saliva into the sap which may kill the plant. It can also introduce viral diseases into the plant.
Effects
Cocoa myriads cause die back disease which reduces the growth of cocoa plant. Fruit yield is reduced.
Control
Spray the cocoa farm with kokotine or gammalin 20
Yam Beetle (Heteroligusmeles)
Life History
The mating of the female and the male yam beetles takes place between November and December in riverine areas and fertilized eggs are laid. Between December and February, eggs hatch into larvae that feed on the decayed organic substances. The larvae melt thrice before developing into pupae. In March, the pupae develop into adults after moulting. The adults then fly to areas where yams are planted between April and June. They dig into the soil to search for yam tubers. When they eventually come in contact with tubers, they feed on them and seriously damage the tubers. Between October and November, the adult yam beetles undergo breeding migration to the riverine areas again for mating.
Effects
Adult beetles feed on yam tubers causing serious damage to the tubers and render the tubers valueless. If the tubers are attacked at early stage, the yield becomes poor.
Control
Dust yam or yam sets with Aldrin before planting.
Evaluation
Examples of Pests of Crops, their Effects and Control (Summary)
PESTS | EFFECTS | CONTROL |
| Nymphs and adults feed on leaves and shoots thereby reducing yield. | Spray with gammalin 20 |
| Adults feed on yam tubers rendering the tubers valueless or causing poor yield | Dust yam or yam sets with aldrin before planting. |
| Piercing and sucking insects that attack young shoots of cocoa introducing toxic saliva and viral diseases into the plants. This may kill the plants, reduces the growth and fruit yield. | Spray cocoa farm with kokotine or gammalin 20. |
| They suck sap of cassava which makes the shoots to develop bunchy tops; the leaves die and drop resulting in low root tubers. | Dig cassava cuttings in 0.1% rogor before planting. |
| Field to store pests. Larvae feeds on bean seed bore holes into them thereby reducing the quantity and quality of the grains. | Fumigating the store with insecticides and early harvesting. |
| Feeds on cotton seeds and stains lint. | Spray suitable insecticides |
| Destroy tubers, fruits and shoots of crops by feeding on them. | Trapping, shooting and clearing their hide out by proper weeding. |
| Feed on grains, plantains and other crops | Chasing away |
Evaluation
PestsandParasitesofLivestockandtheirEffects
A parasite is an organism living in or on another organism called host having a harmful effect on the host as a result of the association. Parasite which lives inside its host is called endoparasite e.g. tapeworm, roundworm, liver fluke. Parasite which lives on or outside the host is called ectoparasite e.g. ticks, lice and mite.
Examples of Animal Pests, their Effects and Control
PARASITE | HOST | EFFECTS/ECONOMIC IMPORTANCE | CONTROL |
| Cattle, goats, sheep | Suck blood which result in anaemia, restlessness, sores on the skin of animals and loss of weight. They also transmit viruses and protozoa that cause diseases | Spray animal houses with insecticides, remove the ticks from the body of the animals |
| Cysts are picked up when animals drink water and feed on grasses. The cyst develops into a young fluke which burrows through the wall of the small intestine and liver. This affects digestion; result in liver rot, leading to drowsiness and death. | Destroy water snail, an intermediate host, treat pools with copper sulphate. | |
| Cattle, pigs | Feeds on digested food from the host which results in slow growth, indigestion and constipation, loss of appetite, weakness & death. | Deworm animals regularly, good sanitary measure |
| Birds | Suck blood of their hosts resulting in great irritation, restlessness, loss of weight and low productivity. They also transmit disease pathogens. | Prevent over crowding, good sanitary measures and use of insecticide (DDT) |
| Cattle | Suck blood and transmits trypanosome (a protozoan parasite) which causes sleeping sickness anaemia and loss of weight. | Clearing bushes around a farmland, use of insecticide |
Economic Importance of Pests
Evaluation
Diseases
A disease is a change of the plant or animal from the normal state of health, presenting marked symptom or outward visible signs in the organism. Disease pathogens are disease causing organisms, which include bacteria, viruses, fungi, nematodes and protozoan.
Diseases of Crops, Effects and Control
NAME OF DISEASE | CAUSATIVE ORGANISMS | SYMPTOMS | CONTROL |
| Fungus | Cob and grains covered with black spores, premature death. | Apply fungicides before planting. |
| Virus | Leaves curl and turn yellow, show mottling and wrinkles, leads to death. | Uproot and burn infected plants. Plant resistant varieties |
| Fungus | Brown spots on leaves, leaves dry up. | Use resistant variety, apply fungicide. |
| Virus | Distorted leaves, yellow patches on leaves, stunted growth | Plant resistant varieties |
| Fungus (Phytophytorapalmivora | Brown spots on pods. The pods turn black and dry up | Apply fungicides. Remove and burn all infected pods |
| Bacterium | Leaves wilt and fall off | Early planting, crop rotation |
| Virus | Stems and roots become swollen, leave chlorolysis | Burn infected plants, use resistant varieties |
Evaluation
Livestock Diseases, Effect and Control
NAME OF DISEASE | CAUSATIVE ORGANISMS | SYMPTOMS | CONTROL |
| Virus | Neck twisting, paralysis of legs, respiratory and nervous disorder, low productivity and death | Sanitation, vaccination |
| Virus | High fever and diarrhea | Isolation of infected animal, vaccination |
| Bacteria | Swellings in the neck, and lower abdomen, fever, blood stained discharge from the nostrils | Immunizatio, sanitation |
| Protozoan | Blood stool, affects intestines | Sanitation |
| Protozoan (trypanosome) | Intermittent fever, general body weakness | Spray tse-tse fly with insecticide, rear resistant breed |
Evaluation
GeneralEffectsof Pests&Diseases
GeneralControlofPests& Diseases
General Evaluation
Reading Assignment: College Biology by IdodoUmeh. Chapter 23, page
WEEKEND ASSIGNMENT
Theory
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