Crop Plants: Pest Control (Edexcel IGCSE Science)
Exam board Pearson Edexcel · IGCSEUpdated 2026-07-02
Spec point —
6.4· understand the reasons for pest control and the advantages and disadvantages of using pesticides and biological control with crop plants
Crop Plants: Pest Control
Using pest control to increase crop yields
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Another key way that modern technology has increased food supply is through the use of pesticides
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Pesticides are chemicals that kill unwanted species, helping to reduce damage to crops and increase yields by controlling competition from other plants and pests:
- Insects and other animals can damage crops by eating them
- Weeds compete with crops for space, water, and nutrients.
- Fungi can infect crops and spread diseases that reduce growth and yield.
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All of these problems can be managed using chemical control (pesticides) or biological control (introducing other species)
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Examples of pesticides:
- Insecticides – kill insect pests
- Herbicides – kill weed species
- Fungicides – kill fungal pests
Advantages and disadvantages of pesticides table
| Advantages | Disadvantages |
|---|---|
| Easily accessible and relatively cheap | Organisms they are meant to kill can develop resistance to them |
| Have an immediate effect | They are non-specific chemicals and can often kill other beneficial organisms (e.g., some insecticides might kill bees, which are important pollinators of crops) |
| Kills the entire population of pests | They can be persistent chemicals – this means they do not break down in the body and can accumulate in great concentrations at the top of food chains and harm top predators (known as bioaccumulation) |
| Need to be repeatedly applied |
Biological control
- Biological control involves using a natural predator to eat the pest species and therefore reduce the impact of the pest on crop yields
- This can happen naturally – for example, ladybirds eat aphids
- Usually, a species is introduced specifically to prey on the pest species – for example, parasitic wasps can control whitefly in glasshouse tomato crops
- As they are based on a predator-prey cycle, they do not completely remove a pest, but keep it at lower levels
Advantages and disadvantages of biological control table
| Advantages | Disadvantages |
|---|---|
| Natural method - no pollution | May eat other organisms instead of the pest |
| No resistance | Takes a longer period of time to be effective |
| Can target specific species | Cannot kill entire population - some pests will always be present |
| Long lasting | May not adapt to new environment or may move out of the area |
| Does not need to be repeatedly applied | May become a pest itself |
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