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Q.(a) Organic farmers prefer biological control of diseases and pests to the use of chemicals for the same purpose. Justify.

(b) Give an example of a bacterium, a fungus and an insect that are used as biocontrol agents.
Punjab PsebCBSE Class XII Board 2018Subjective· 3mImportance★★★★★
100% · 80/80 Questions
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(a) Chemicals are toxic and pollute the environment and harm non-target life, whereas biological control is eco-friendly and pest-specific. (b) Bacterium — Bacillus thuringiensis; Fungus — Trichoderma; Insect — Ladybird (beetle).

Concept. Biological control (biocontrol) is the use of biological methods — living organisms — for controlling plant diseases and pests, rather than chemical pesticides, insecticides and herbicides. It is central to organic farming, which stresses a broad ecological understanding of pests and their life cycles.

(a) Why organic farmers prefer biological control.

  1. Chemical pesticides and herbicides are toxic and extremely harmful — they pollute the soil, water and air.
  2. They kill non-target and beneficial organisms as well (useful insects, birds, etc.) and can harm humans through residues in food.
  3. Pests may develop resistance to chemicals, and chemicals leave persistent residues in the environment.
  4. In contrast, biocontrol agents are eco-friendly, largely pest-specific, do not pollute, and keep the pest population in check as part of a balanced ecosystem — targeting the harmful organism without eradicating everything.

(b) Examples of biocontrol agents. …

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