UPSC Prelims 2024 CSAT Paper II · Q53 of 79 Comprehension medium

Passage

Passage-3 Evolution has endowed caterpillars that feed on corn with a unique ability, they can induce the plant to turn off its defence against insect predators. This helps caterpillars to eat more and grow faster. The agent that causes this effect is the caterpillar's faeces or frass. The find could throw new light on compounds associated with plant response to pathogens like fungi or bacteria.

Which one of the following statements best reflects the most logical, rational and practical message conveyed by the passage?

  1. (a) Farmers can use caterpillars to feed on weeds in their crop fields/plantations.
  2. (b) This finding can help in the development of clinically useful antimicrobial compounds.
  3. (c) This finding can help in the development of organic, ecologically sustainable pesticides. ✓ UPSC's answer
  4. (d) Caterpillars can be genetically modified to be predators of the other plant pests.

Why the answer is (c)

• The passage states that caterpillar frass induces corn plants to turn off their defense mechanisms against insect predators.

• This specific biological mechanism allows caterpillars to feed more efficiently and grow faster by suppressing the host plant's natural resistance.

• The text explicitly links this finding to compounds associated with plant responses to pathogens, suggesting a broader application in understanding plant-insect interactions.

• A practical and rational application of this knowledge would be to develop agents that manipulate plant defenses to control pests without synthetic chemicals.

• Therefore, the finding supports the development of organic, ecologically sustainable pesticides that leverage natural plant responses rather than toxic external inputs.

Why the other options are wrong

(a) Farmers can use caterpillars to feed on weeds in their crop fields/plantations.
The passage describes caterpillars feeding on corn, not weeds, and using them for weed control is not a logical inference from the specific mechanism described.
(b) This finding can help in the development of clinically useful antimicrobial compounds.
While the passage mentions pathogens, the primary focus is on insect predators and plant defense against them, not the direct development of clinical antimicrobial compounds for human use.
(d) Caterpillars can be genetically modified to be predators of the other plant pests.
The passage discusses natural evolutionary traits and frass effects, not genetic modification of caterpillars to become predators of other pests.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2024, held on 16 June 2024. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.

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