Relevance: GS-III – Environment & Biodiversity

The issue in one breath.

Invasive alien species are organisms moved by people outside their natural range that establish, spread fast and cause harm to biodiversity, farms, fisheries and health.

Know a few, habitat-wise (memory aids)

• Land plants: Lantana camara (fires, chokes forests), Parthenium hysterophorus (crop losses, allergies), Prosopis juliflora (alters drylands), Chromolaena odorata.
  
• Wetlands and rivers: Eichhornia crassipes (water hyacinth), Salvinia molesta (covers tanks), fish like Clarias gariepinus (African catfish) and tilapias (Oreochromis spp.).
  
• Pests and others: fall armyworm (Spodoptera frugiperda) on maize, apple snail (Pomacea canaliculata), yellow crazy ant on islands.
  

Why they matter

They push out native species, block canals, fuel fires, spread diseases, and cost farmers money. On islands and small wetlands, a single invader can wipe out local species.

India’s rulebook and response

• Prevention: Plant Quarantine Order, 2003 and Livestock Importation Act screen seeds, saplings and live animals.
  
• Control powers: Wildlife (Protection) Act, 1972 as amended in 2022 enables regulation of invasive alien species; Biological Diversity Act, 2002 supports local registers and action.
  
• Field playbook: early detection and rapid response, safe removal and disposal, no re-seeding or sale that spreads the species, and restoration with native plants.
  
• People power: citizen-science alerts from fishers, farmers and trekkers; positive lists for the pet and aquarium trade.
  

Key terms
biosecurity • pathway management • propagule pressure • allelopathy • early detection and rapid response • restoration ecology

Exam hook

UPSC Prelims question
Which of the following is an invasive alien pair correctly matched with its impact?
(a) Lantana camara — improves forest regeneration
(b) Eichhornia crassipes — clogs wetlands and depletes oxygen
(c) Prosopis juliflora — increases native grass diversity
(d) Clarias gariepinus — boosts native fish reproduction
Answer: (b)

One-line wrap
Block the entry, act early, remove safely, and restore with natives—that is India’s best defence against invasive aliens.