Question 103·Easy·Central Ideas and Details
During a recent locust outbreak in northern provinces, entomologist Lin Wei investigated a naturally occurring soil fungus that infects insects. In controlled field trials, the fungus killed locust nymphs within 48 hours and produced airborne spores that traveled to nearby swarms. Wei says the results indicate that the fungus could reduce reliance on chemical pesticides while keeping locust populations in check.
Which choice best states the main idea of the text?
For main-idea questions on the SAT, first restate the passage in 1–2 simple sentences without looking at the choices. Then, compare each option to your summary and eliminate any that (1) focus on a minor detail instead of the overall point, (2) add information or attitudes not in the text, or (3) contradict what the author clearly states. Finally, pick the choice that best matches the author’s overall conclusion or purpose, often found near the end of a short passage.
Hints
Focus on the author’s purpose
Ask yourself: Why is Lin Wei’s research being described? Is the paragraph mainly about locust damage, about the fungus itself, or about what the research shows?
Look closely at the last sentence
Pay special attention to what Wei says the results indicate—this often states the main takeaway or conclusion of a short passage.
Watch for contradictions and exaggerations
Check whether any answer choice adds ideas the passage never mentions (like strong warnings) or directly disagrees with Wei’s statement about reducing reliance on chemical pesticides.
Step-by-step Explanation
Identify the task: main idea, not a detail
The question asks for the choice that best states the main idea of the text. This means you should look for an answer that captures what the entire passage is mostly about, not just one fact or a minor point.
Summarize the passage in your own words
Briefly restate the paragraph:
- Lin Wei studies a soil fungus that infects insects.
- In field trials, the fungus killed locust nymphs quickly (within 48 hours).
- It produced spores that spread to other nearby locust swarms.
- Wei concludes that this fungus could help control locust populations and reduce the need for chemical pesticides.
So overall, the focus is on Wei’s research and what it suggests about using the fungus to manage locusts in an environmentally friendly way.
Match that summary to the answer choices
Now compare your summary to each option:
- Eliminate choices that talk about something the passage only hints at briefly (like crop damage) or doesn’t say at all (like needing close monitoring of the fungus).
- Also remove any choice that contradicts Wei’s conclusion about reducing reliance on chemical pesticides.
- Keep the option that mentions Wei’s research, the fungus, controlling locusts, and reducing pesticide use.
Confirm the best match
The only choice that accurately reflects the passage’s overall focus—Wei’s research showing that a natural fungus may be an effective, environmentally friendly way to control locust outbreaks and reduce use of chemical pesticides—is:
Research by Lin Wei suggests a naturally occurring fungus could serve as an effective, environmentally friendly method to manage locust outbreaks.