Which one of the following is used in preparing a natural mosquito repellent?
Contents14
- ACongress grass
- BElephant grass
- CLemongrass
- DNut grass
Show answer
Answer: (C) Lemongrass
Lemongrass contains an essential oil called Citronella, which is the most widely used natural mosquito repellent.
Citronella is registered with the US FDA and is found in mosquito-repellent candles, sprays, and lotions.
Congress grass (Parthenium) is a weed that causes allergies.
Elephant grass is used as fodder.
Nut grass is a common weed.
None of these have mosquito repellent properties.
Answer: (c).
Lemongrass contains citronella oil, which is the most widely used natural mosquito repellent and is registered with the US FDA.
During COVID-19 pandemic years, there was increased focus on natural immunity boosters and herbal remedies, making traditional plant uses more relevant for UPSC.
The question tests practical knowledge of medicinal plants versus common weeds - students must distinguish between beneficial plants and harmful ones like Parthenium.
Lemongrass & Citronella Oil
Environment Lemongrass natural mosquito repellent
Lemongrass & Citronella: Natural Mosquito Repellent Properties
Lemongrass contains citronella oil - the most widely used natural mosquito repellent
Citronella is US FDA registered as safe mosquito repellent
Found in commercial repellent candles, sprays, and lotions
Cymbopogon genus includes both lemongrass and citronella grass
What Makes It Work
Lemongrass (Cymbopogon citratus) produces an essential oil rich in citronella - a natural compound that masks scents mosquitoes use to locate humans. This makes it the most effective plant-based mosquito deterrent.
Lemongrass vs Other Repellent Plants
Plant | Active Compound | Effectiveness | Commercial Use |
|---|---|---|---|
Lemongrass | Citronella oil | High - FDA registered | Candles, sprays, lotions |
Neem | Azadirachtin | Moderate | Traditional use mainly |
Basil | Eugenol | Low-Moderate | Limited commercial use |
Marigold | Pyrethrum compounds | Moderate | Garden companion planting |
Commercial Applications
Citronella candles - burn to release repellent compounds in outdoor areas
Topical sprays and lotions - applied directly on skin for personal protection
Essential oil extraction - steam distillation from fresh lemongrass leaves
Natural alternative to DEET-based synthetic repellents
Trap: All grasses mentioned sound similar - only lemongrass has repellent properties
Trap: Congress grass (Parthenium) is actually harmful - causes allergies, not repellent
Trap: Elephant grass and nut grass are common plants but have no mosquito-repelling compounds
Congress Grass (Parthenium)
Environment Congress grass
Congress Grass (Parthenium): Invasive Weed & Health Hazard
Congress grass = Parthenium hysterophorus - major invasive weed in India
Causes severe allergic reactions - skin rashes, asthma, hay fever
No mosquito repellent properties - opposite of beneficial
Originally from Central America - introduced accidentally to India
Why It's Problematic
Parthenium hysterophorus is among India's most dangerous invasive weeds. It releases allergens that cause respiratory problems and skin disorders in humans and animals. The plant also reduces crop yields by competing for resources.
Health & Environmental Impact
Allergic dermatitis - direct skin contact causes severe rashes and blisters
Respiratory issues - pollen triggers asthma, hay fever, and bronchitis
Crop displacement - reduces agricultural productivity by 40-90% in infested areas
Livestock poisoning - animals grazing on it develop health problems
Rapid spread - one plant produces up to 25,000 seeds annually
Trap: Name suggests political connection - actually named after grass-like appearance, not Indian National Congress
Trap: Sounds beneficial like other 'grass' options - but it's a harmful invasive weed
Trap: Students might think all plants have some beneficial use - Parthenium is purely problematic
Fodder Grasses & Agricultural Uses
Environment Elephant grass Nut grass
Elephant Grass & Nut Grass: Agricultural & Ecological Roles
Elephant grass (Pennisetum purpureum) - high-quality livestock fodder
Nut grass (Cyperus rotundus) - persistent agricultural weed
Neither has mosquito repellent properties - purely agricultural significance
Both are perennial grasses but serve different purposes
Elephant Grass vs Nut Grass
Aspect | Elephant Grass | Nut Grass |
|---|---|---|
Scientific Name | Pennisetum purpureum | Cyperus rotundus |
Primary Use | Livestock fodder | Medicinal (traditional) |
Agricultural Status | Beneficial - cultivated | Weed - controlled |
Growth Pattern | Tall (up to 4 meters) | Low-growing with underground tubers |
Economic Value | High - commercial fodder | Negative - crop competitor |
Elephant Grass Benefits
High protein content - excellent nutritional value for cattle and buffalo
Fast growing - can be harvested multiple times per year
Drought resistant - suitable for semi-arid regions
Soil conservation - deep roots prevent erosion
Nut Grass Challenges
Persistent weed - underground tubers make it difficult to eradicate
Crop competition - reduces yields of rice, sugarcane, and cotton
Traditional medicine - used in Ayurveda despite being agricultural pest
Global distribution - found across tropical and subtropical regions
Natural vs Synthetic Mosquito Repellents
Environment
Natural vs Synthetic Mosquito Repellents: Effectiveness & Safety
DEET is most effective synthetic repellent - up to 12 hours protection
Citronella (natural) provides 2-4 hours protection with fewer side effects
Natural repellents are FDA approved and environmentally safer
Choice depends on duration needed vs safety concerns
Repellent Types Comparison
Type | Active Ingredient | Protection Duration | Safety Profile | Best Use |
|---|---|---|---|---|
Synthetic | DEET (N,N-Diethyl-meta-toluamide) | 8-12 hours | Skin irritation possible | Long outdoor exposure |
Natural | Citronella oil | 2-4 hours | Very safe - minimal side effects | Short-term use, sensitive skin |
Synthetic | Picaridin | 6-8 hours | Less irritating than DEET | Moderate outdoor activities |
Natural | Neem oil | 2-3 hours | Safe - traditional use | Organic farming, home use |
Vector-Borne Disease Context
Malaria prevention - WHO recommends DEET for high-risk areas
Dengue and Chikungunya - Aedes mosquitoes active during day, natural repellents suitable
Children and pregnant women - natural options preferred due to safety profile
Resistance development - synthetic compounds may lose effectiveness over time
Trap: Students assume 'natural' always means less effective - citronella is FDA registered and commercially viable
Trap: All plant extracts don't repel mosquitoes - only specific compounds like citronella work
Trap: Duration matters - natural repellents need more frequent application than synthetic ones