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

  • Congress grass 
  • Elephant grass
  • Lemongrass
  • Nut grass

Answer: (c) Lemongrass

Congress grass
  • Parthenium hysterophorus: In India, it is locally known as carrot grass, congress grass or Gajar Ghas or Dhanura. It is a common invasive species in India, Australia, and parts of Africa.
  • Parthenium hysterophorus invades disturbed land, including roadsides. It infests pastures and farmland, causing often disastrous loss of yield, as reflected in common names such as famine weed.
  • The plant produces allelopathic chemicals that suppress crop and pasture plants, and allergens that affect humans and livestock. It also frequently causes pollen allergies.
  • Contact with the plant causes dermatitis and respiratory malfunction in humans, and dermatitis in cattle and domestic animals.
Elephant grass
  • Cenchrus purpureus, also known as Napier grass, elephant grass or Uganda grass, is a species of perennial tropical grass native to the African grasslands.
  • It has low water and nutrient requirements, and therefore can make use of otherwise uncultivated lands.
  • This wild species has been used primarily for grazing, recently, however, it has been used as part of a push–pull agricultural pest management strategy.
  • Napier grasses improve soil fertility, and protect arid land from soil erosion.
  • It is also utilized for firebreaks, windbreaks, in paper pulp production and most recently to produce bio-oil, biogas and charcoal.
Lemongrass
  • Cymbopogon also known as lemongrass, barbed wire grass, silky heads, Cochin grass, Malabar grass, oily heads, citronella grass or fever grass, is a genus of Asian, African, Australian, and tropical island plants in the grass family.
  • These species are used for the production of citronella oil, which is used in soaps, as an insect repellent (especially mosquitoes and houseflies) in insect sprays and candles, and aromatherapy.
  • The principal chemical constituents of citronella, geraniol and citronellol, are antiseptics, hence their use in household disinfectants and soaps.
    • Besides oil production, citronella grass is also used for culinary purposes as a flavoring.
  • In India, It is used as a medical herb and in perfumes. It is consumed as a tea for anxiety in Brazilian folk medicine.
Nut grass
  • Nutgrass is considered one of the world’s worse weeds.
  • Nutgrass is a weed of major economic important infesting many crops, and also an environmental weed through its ability to invade native vegetation.