Question 58 from UPSC CSE 2021 - Environment

Question

Which one of the following is used in preparing a natural mosquito repellent?

Accepted Answer

Correct Option: C. Lemongrass

Strategy: Focus on the plant recognized for natural mosquito repellent properties. Lemongrass contains oils like citronella, widely known for their efficacy against mosquitoes. Congress grass, elephant grass, and nut grass are not typically associated with mosquito repellency. Recognizing 'lemongrass' as the plant yields the answer directly.

Key Info: **Lemongrass**
Lemongrass (Cymbopogon citratus and related species) is valued for its fragrant oil, especially citronella, which is widely used in natural mosquito repellents. Citronella oil masks scents attractive to mosquitoes and has mild insecticidal effects. It is found in sprays, lotions, candles, and creams. The FDA has recognized citronella as a safe, natural mosquito repellent. Lemongrass can also be grown around homes to help reduce mosquito presence.

**Other Grasses**
- **Congress grass** (Parthenium hysterophorus) is an invasive and toxic weed, not suitable for repellent use.
- **Elephant grass** (Pennisetum purpureum) is a tall fodder grass with no known mosquito-repellent properties.
- **Nut grass** (Cyperus rotundus) is considered a weed and lacks established mosquito-repellent properties.

**Natural vs. Synthetic Repellents**
Natural repellents like citronella are often preferred over synthetic options such as DEET due to safety and lower toxicity, though they may require more frequent application.

Answer

Option A: Congress grass

Answer

Option B: Elephant grass

Answer

Option D: Nut grass