Describe how farmers can use biological control to reduce crop losses caused by pests.

Eduqas GCSE Biology — 6.4 Biological challenges of increasing food yields · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Farmers face the challenge of increasing food yields to feed a growing global population. Pests can destroy crops and significantly reduce the amount of food available for harvest.

Model answer (4 marks)

Introduce a natural predator, parasite or pathogen that attacks the pest.
The natural enemy reduces the pest population by killing or parasitising the pest.
With fewer pests, crop damage is lowered and less of the crop is eaten.
This method avoids chemical pollution and pesticide residues entering the food chain or environment.

Examiner tips

  • Use the exact wording from the mark scheme (e.g., "natural predator", "reduces the pest population", "no chemical pollution").
  • Show the causal chain: introduction → pest reduction → crop protection → environmental benefit.

Common mistakes

  • Confusing biological control with chemical pesticides; failing to mention the environmental advantage.
  • Using vague terms like "natural methods" without specifying predators, parasites or pathogens.

Mark scheme (4 marks)

  1. A natural predator / parasite / pathogen of the pest is introduced
  2. The natural predator / parasite / pathogen reduces the pest population / kills the pest
  3. This reduces damage to crops / less crop is eaten by the pest
  4. An advantage over pesticides: no chemical pollution / pesticide residues do not enter the food chain / environment

Key terms in this question

biological control · pest

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