University of Bristol
Wellcome Trust
Recommended by:
Society of Biology
PEEP for Physics & Ethics at GCSE


Biological Pest Control – a better way to reduce pests.

An example in more detail:

The parasitic wasp (Ecasaria Formosa) and the control of whitefly (Trialeurodes vaporarium
  • A glasshouse is an ideal place for growing plants but also an ideal habitat for a pest.
  • Tomatoes and cucumbers can have a serious pest called a white fly.
  • This small moth-like insect lives for 35 days and each female can produce up to 500 eggs.
  • The adult and larva feed by sucking sap. They produce a sticky sugary secretion which encourages fungal growth on the leaves and fruits. This seriously disrupts photosynthesis and therefore crop yields.
  • The whitefly can be controlled by insecticides although the pest is now showing resistance.
  • Biological control involves introducing a parasitic wasp (Encarsia formosa) into the glasshouse. The female wasps lay eggs on the whitefly. These hatch into minute larvae which pupate and kill the host whitefly.
  • These emergent adults then continue the cycle, females laying 60-100 eggs.
  • The method is cheap and highly effective in controlling the pest.

What happens when biological control does not work effectively? Is integrated control the future?

  • Often biological control cannot work entirely on its own as pest numbers are difficult to control, especially at the beginning of an infestation.
  • New methods now use biological control in conjunction with other control methods – this is known as integrated control.
  • Additional methods could include:
    • Producing pest-resistant crops.
    • Cultivation techniques to reduce pest numbers.
    • Targeted application of highly-specific pesticides.


Next: Pollution from fossil fuels

Emerging female
Parasitized whitefly
Emergence hole

Click to enlarge photos
Photos copyright © 2003
The Regents of the
University of California.
All rights reserved.

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