Crop Plants: Pest Control (Edexcel IGCSE Biology)

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Crop Plants: Pest Control

Using pest control to increase crop yields

  • Pests such as insects and other animals can damage crops by eating them
  • Weeds can outcompete crop plants for space, water and soil nutrients
  • Fungi can infect crop plants and spread disease which can affect growth and yield
  • All of these can be controlled by using pesticides (chemical control) or by introducing other species (biological control)
  • Examples of pesticides include:
    • Insecticides kill insect pests
    • Herbicides kill plant pests
    • 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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Lára

Author: Lára

Expertise: Biology Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.