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?

The correct option is: "This finding can help in the development of organic, ecologically sustainable pesticides."

Step-by-Step Explanation:

1. Analyze the core information in the passage:
The passage describes a biological mechanism where caterpillars feeding on corn use their feces (frass) to turn off the corn plant's natural defense mechanism against insect predators. This represents a biochemical interaction between a herbivorous insect and a plant host.

2. Analyze the implications of the finding:
By understanding the specific compound or agent in the caterpillar's frass that manipulates the plant's defense pathways, scientists can replicate, modify, or use this mechanism to manage plant-insect relations. In agriculture, understanding how to control or trigger plant defenses is key to pest management.

3. Evaluate the correct option:
Since the agent in the frass is a naturally occurring biological substance that alters plant defense responses, studying it can lead to the creation of targeted, organic, and ecologically sustainable pest control solutions (pesticides) that leverage these natural biochemical pathways rather than relying on synthetic, harmful chemicals.

4. Why other options are less logical or practical based on the text:
- Farmers using caterpillars to feed on weeds: The passage specifically mentions caterpillars feeding on corn (a crop, not a weed) and turning off defenses to eat more of the crop. Using them in crop fields would harm the crops.
- Development of clinically useful antimicrobial compounds: The passage mentions plant responses to pathogens like fungi/bacteria, but translating this directly to clinical (human) antimicrobials is a far stretch compared to the direct agricultural application of plant defenses.
- Genetically modifying caterpillars to be predators: Caterpillars are herbivores (eating plants like corn), not predators of other pests, and genetically modifying them to become carnivores/predators is biologically impractical compared to using the chemical findings for pesticides.