Effect or Economic importance of insect pests in crop production
- They destroy crop by biting, chewing, piercing and defoliation activities
- Reduction in farmer’s profit.
- Some insects are disease carriers.
- Increased rate of crop production
- Reduction in the viability of stored produce
- They can cause total death of crops
- Spot of injuries by insect may predispose crop to disease attack
- They render farm products unattractive and unmarketable
Prevention and Control of Pests
Pest control can be done via 3 methods – physical, chemical and cultural.
Physical Control – This involves the removal of insect by
- hand picking 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 practices to prevent or control pests especially on the field. Examples of cultural control include
- Bush fallowing
- Crop rotation change in the time of planting
- Regular weeding
- Proper timing of planting
- Use of pest resistant varieties
- Burning of crop residues
- Proper time of harvesting
- Appropriate tillage operations
- Close season practices
Biological Control – This involves the introduction of the natural enemies of pests to control or keep the pests population under control. Such enemies eat up or feed on these pests thereby reducing the population of the pests.
Chemical Control –
Chemical control involves the use of chemicals called pesticides to control pests of crop plants. These chemicals which are in form of powder, liquid, granules and tablets are used on the insects by various methods like spraying or dustings seeds or plants to check pests. Examples of such chemicals include:
- Pesticides – chemicals to control pests
- Insecticides – chemicals to control insects
- Rodenticides – chemicals to control rodents
- Avicides – chemicals to control birds
- Nematicides – chemicals to control nematodes
The micronutrients are boron, chlorine, cooper, iron, manganese, molybdenum, and zinc. These plant food elements are used in very small amounts, but they are just as important to plant development and profitable crop production as the major nutrients. Especially, they work “behind the scene” as activators of many plant functions.
Insecticide
An insecticide is a chemical prepared used for the control of pest.
Types of insecticides
There are 4 major forms of insecticides used in the control of pest.
a. Powder – mode of action is by contact
b. Liquid – mode of action is systemic
c. Granules – mode of action is through stomach
d. Gaseous – mode of action is by fumigation
Crops and Major pests
| Crop | Pests |
| Beans | Beans weevils (Callosobronchus maculatus) |
| Rice | Rice weevil (Sitophilus oryzae), stem borers, army worms and leaf rollers |
| Maize | Maize weevils (sitophilus zea), stem borers and army worms |
| Yam | Yam beetles and rodents |
| Cocoa | Stem borers, root mealy bug, aphids, black tea thrips, and scales |
| Groundnut | Leaf worm aphids, boll worms, snail and hoppers |
| Cotton | Cotton strainers and boll worms |
| Sorghum | Weevils, boll worms, aphids and sorghum midge |
| Stored grains | Weevils |
Effects or Economic Importance of Insect Pests in Crop Production
- Insect pests destroy crops in the field through their biting, chewing, boring, sucking and defoliation activities
- They cause reduction in the viability of stored produce
- Site of injuries by insects may predispose crops to disease attack
- 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
Side effects of Various preventive measures
Cultural Method of Control
- Use of fire to kill harmful pest may result in destruction of other useful organisms
- Resistant varieties may adapt to the environment causing resistance to be shortlived
- Fire may spread to other farms if not properly managed
- Use of fire may cause loss of organic matter of soil and destruction of soil structure
Chemical Method of Control
- Some beneficial insects and soil organisms may be destroyed
- Pests and diseases may develop resistance
- Chemicals used may be toxic to man and crops
- It may leave undesirable residual in the environment
- Some chemicals washed out through water, soil erosion may cause pollution to larger rivers
Biological Method of Control
- New organism introduced may start attacking crops
- Predators expected to control other may rather feed on other beneficial insects
- Introduction of new organisms may cause imbalance in the ecosystem
Practice Questions
Use the options listed to answer the questions 1 – 3 below
Insecticide, Nematicide, Avicides, Pesticides, Rodenticides
- ____ chemical is used to control pests
- ____ chemical is used to control birds
- _____ chemical is used to control nematode
- List three economic importance of pests
- What are the side effects of chemical method