PESTS OF CROPS | MEANING, TYPES, CLASSIFICATION, IMPORTANT

MEANING OF CROP PEST

A crop pest can be defined as any organism capable of causing damage to the crop.

TYPES OF CROP PEST

Crop pests can be categorized into various classes based on the organisms that cause damage. Here are some common types of crop pests:

1. Insects: Insects are one of the most significant groups of crop pests. They include a wide range of pests such as aphids, beetles, caterpillars, grasshoppers, locusts, weevils, whiteflies, and many others. These pests can damage crops by feeding on leaves, stems, roots, fruits, or by transmitting diseases.

2. Birds: Certain bird species can cause damage to crops, especially those that feed on fruits, grains, or seeds. For example, sparrows, blackbirds, and pigeons can cause substantial losses to crops like rice, corn, sunflowers, and grapes.

3. Rodents: Rodents like rats and mice are notorious crop pests. They can feed on various crops, including grains, vegetables, fruits, and stored produce. Rodents not only consume crops but also damage them by gnawing on stems, roots, and fruits.

4. Monkeys: In some regions, monkeys can be significant crop pests, especially in areas where agriculture encroaches upon their natural habitats. Monkeys can damage a variety of crops, such as bananas, papayas, mangoes, and vegetables.

5. Humans (Man): While not a biological pest, human activities can also cause damage to crops. This includes improper farming practices, such as overuse of pesticides, inadequate irrigation, or poor soil management. Human activities can also result in crop losses due to theft, vandalism, or accidental damage.

6. Nematodes: Nematodes are microscopic worms that can be pests of crops. Plant-parasitic nematodes can infest the roots of plants, causing stunted growth, wilting, and reduced yield. Examples of crop-damaging nematodes include root-knot nematodes, cyst nematodes, and lesion nematodes.

It’s important to note that the specific pests that affect crops can vary depending on the geographical location, crop type, and environmental conditions. Integrated pest management (IPM) practices aim to identify and manage these pests effectively through a combination of cultural, biological, and chemical control methods.

CLASSIFICATION OF INSECT PEST

Biting and chewing insects: they possess strong mandible and maxillae (mouth parts) which enable them to bite and chew plant parts e.g termites, grasshoppers, leafworm, mantids, locusts and beetles.
Piercing and sucking insects: they possess stong mouthparts called proboscis which enable them to pierce through plants and suck liquid materials from them. Examples are aphids, cotton strainers, mealy bugs, scale insects, capsids, mirids and white flies.
Burrowing insects: they and their larva stage are capable of burrowing the tissue of the plant parts or fruits or seeds. Examples are bean beetles, stem borers, maize weevils and rice weevils.

IMPORTANT PESTS OF MAJOR CROPS

Pest	Crops Attacked	Natures of Damages and Economic Importance	Prevention and Control Measures
Stem burrower	Cereals e.g. rice, maize, guinea corn.	(i) Larvae bore holes into stems (ii) They eat up the tissues (iii) They weaken the plant	(i) Uproot and burn infected plant (ii) Spray with insecticides e.g. Gammalin 20 (iii) Reduced growth and yield (iv) Early planting (v) 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	(i) Crop rotation (ii) Early harvesting (iii) Spray with insecticides (iv) Introduce diseases.
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	Legumes e.g. cowpea, soyabeans	(i) They eat up the leaves (ii) Reduce photosynthesis (iii) Reduced yield	(i) Spray with insecticides (ii) Use pest-resistant varieties.
Cocoa mirids (capsids)	Beverages e.g. Cocoa	(i) They inject toxic saliva into plant (ii) Transmits fungal diseases (iii) Reduced yield (iv) Stunted growth	(i) Spray with insecticides e.g. Gammalin 20 (ii) Regular Weeding
Yam beetles	Tubers e.g yam	(i) Boreholes into yam tubers (ii) Reduced yield (iii) Reduction in quality and market value	(i) Dust yam setts with Adrin dust before planting (ii) Crop rotation
Cassava Mealybugs	Tubers e.g cassava	(i) Twisting of stem and reduced internodes (ii) Swelling of shoots (iii) Reduced yield	(i) Early planting (ii) Use pest-resistant varieties. (iii) Cutting treatment (iv) Spray with insecticides
Green Spidermite	Tubers e.g cassava	(i) They feed on the leaves (ii) Reduce rate of photosynthesis (iii) Reduced 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 feeds 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	Vegetable	(i) Rolling and twisting of leaves (ii) Reduction in rate of photosynthesis (iii) Reduced yield	(i) Spray with insecticides e.g. Vetox 85
Leaf beetle	Vegetables e.g. pepper, okra and tomato	(i) They eat up leaves and stems (ii) Reduced photosynthesis (iii) Reduction in yield and quality	(iv) Spray with appropriate insecticides e.g. Vetox 85
Bean beetle, grain weevils	Stored produce e.g. rice, cowpea and maize.	(i) Boreholes into grains and eat them up (ii) Reduce the quality of stored produce (iii) Reduced farmer’s income (iv) Reduce the market value of grains (v) Reduce viability of insfested 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 pests.
Birds	Rice, maize, millets and sorghum	(i) Feed on grains in the field (ii) Reduction in quality and yield (iii) Reduction in income of farmers	(i) Use of bird scarer or scare crow (ii) Use of cage traps with baits (iii) Shooting with catapult (iv) Drumming or noise making on the farm (v) Use of explosive mechanism at regular intervals (vi) Use of avicides (vii) Fencing /Screening farms in greenhouse
Rodents e.g. bush rabbit, rats and squirrel	Rice, yam, cassava and fruits	(i) They feed on crops (ii) Destroy whole plant (iii) Reduction in yield (iv) Increase in cost of production	(i) Trapping with braits. (ii) Use of rodenticides (iii) Use of string/wire traps (iv) Use of predators e.g. dogs and cats (v) Clean weeding of farms (vi) Shooting and fencing (vii) Use of pit traps
Monkeys	Cocoa mango, banana, and 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.

CONOMIC IMPORTANCE OF INSECT PESTS IN CROP PRODUCTION

They destroy crops in the fields through their biting, chewing, boring, sucking and defoliation activities.
They cause reduction in viability of stored produce
Spot of injuries by insect pests predispose crops to pathogen attack
They increase the cost of production as they are being controlled
They render vegetables and fruits unattractive and unmarketable
Some are of vectors of disease
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.

GENERAL EVALUATION

What are pathogens?
List five pathogens you know
List four economic importance of insect pest