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Microbes in Human Welfare — BIOLOGY STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYMicrobes in Human Welfare5 Marks
Question
Why should biological control of pests and pathogens be preferred to the conventional use of chemical pesticides? Explain how the following microbes act as biocontrol agents:
  1. Bacillus thuringiensis.
  2. Nucleopoly hedrovirus.
✓

Answer

Biological control of pests and pathogens is preferred because:
  1. The chemicals cause pollution of water bodies as well as ground water, besides getting stored in the plants.
  2. The chemicals are toxic thus extremely harmful to human beings and other animals.
  1. Bacillus thuringiensis: B. thuringiensis toxin genes when introduced into plant, become resistant to attack by insect pests. They are available in sachets as dried spores, which are mixed with water and sprayed onto vulnerable plants. When they are eaten by the insect larvae, the toxin is released in the gut where it becomes active and kills the larvae. Specific Bt toxin genes obtained from B. thuringiensis are used in several crop plants which make them resistant to insect pest.
  2. Nucleopolyhedrovirus: These viruses are excellent candidates for species-specific, narrow spectrum insecticidal applications. This is especially desirable when beneficial insects are being conserved to aid in an overall integrated pest management (IPM) programme.

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