Invasive Alien Species | 26 Aug 2025

Source: TH

Why in News?

A recent study estimates that the global economic cost of Invasive Alien Species (1960–2022) exceeds USD 2.2 trillion, with management costs underreported up to 16 times. 

• For India, the study highlights a hidden cost discrepancy of 1.16 billions of times higher than reported figures indicating gross underestimation of financial and administrative measures to manage invasive species.

What are Invasive Alien Species?

• About: Invasive Alien Species are non-native organisms (plants, animals, fungi, or even microbes) introduced beyond their natural range, forming self-sustaining populations. 
  • They outcompete native species, disrupt ecosystems, and cause significant ecological, economic, and social impacts.
  • According to the Convention on Biological Diversity (CBD), IAS are species that can “arrive, survive, and thrive”, often outcompeting native species for resources. 
  • In India, the Wildlife Protection Act, 1972 defines IAS as non-native species that threaten wildlife or habitats. 
• Key Invasive Alien Species in India: Animal species like African catfish, Nile tilapia, red-bellied piranha, alligator gar, Red-eared Slider (a North American turtle) and plants like Lantana, Water Hyacinth, and Prosopis juliflora, are among the most widespread invasive species in India.
• Factors Responsible for the Rise of Invasive Alien Species:
  • Globalisation-Linked Dispersal: Increased trade and travel facilitate unintentional spread of species via cargo, ballast water, and transport vehicles. 
    • For instance, the Black Rat, introduced to Australia in the 1800s, is listed among the “World’s Worst” invasive species by the IUCN.
    • Also, the Zebra mussel, native to Eurasia, was introduced to the Great Lakes of North America via the ballast water of cargo ships.
  • Climate-Driven Proliferation: Changes in temperature and precipitation create favourable conditions for invasive species and disrupt native species’ life cycles, making them vulnerable to competition and predation.
    • Eg: Warmer conditions accelerate spread of invasive insects, cinnamon fungus, and aquatic species (fish, mollusks), intensifying competition and predation on native species.
  • Habitat Disturbance and Degradation: Human activities that disturb or degrade natural ecosystems, like deforestation, urbanization, and agriculture, can create opportunities for invasive species to colonize. 
    • Eg: Parthenium hysterophorus, commonly known as carrot grass, thrives in disturbed habitats like roadsides and agricultural fields. Its presence is often a sign of environmental degradation.
  • Human Introduction of Exotic Species: Across the world, many invasive alien species have been deliberately introduced by humans for purposes such as ornamental gardening, landscaping, aquaculture, or pest control. 
    • However, these introductions often backfire, as species escape into the wild and outcompete native biodiversity.
    • For instance, Water hyacinth or "Terror of Bengal" was introduced in India because of its beautiful foliage and flowers.

What are the Key Impacts of Invasive Alien Species?

• Ecological Impact: Globally, Invasive Alien Species are one of the 5 major direct drivers of biodiversity loss.
  • They cause the decline or extinction of native species through competition, predation, or disease, disrupting ecosystem functions and leading to ecological imbalance and habitat loss. 
  • Eg: Brown tree snake, accidentally introduced to Guam after World War II, has caused significant ecological damage, leading to the extirpation (local extinction) of many native forest bird species.
• Economic Impact: They impose substantial financial burdens on countries and sectors worldwide, affecting livelihoods in developing countries by impacting agriculture, forestry, and fisheries. 
  • Among Invasive Alien Species, plants are the most economically damaging, with management costs of USD 926.38 billion, followed by arthropods and mammals. 
    • Aquatic species like Water Hyacinth in Lake Victoria have led to tilapia depletion, impacting local fisheries. 
  • Europe incurs the highest absolute costs (71.45% of global expenditure) due to higher agricultural values and management expenses.
• Health Impact: Invasive Alien Species such as Aedes albopictus and Aedes aegypti transmit malaria, Zika, and West Nile Fever, affecting human health. 
  • Many Invasive Alien Species are allergenic or toxic, e.g., Parthenium causes respiratory disorders and skin allergies.
  • Also, crop contamination by invasive weeds also introduces toxic alkaloids into food chains, impacting long-term health.
• Threat Multiplier: IAS like Lantana alter fire regimes, displace native flora, reduce carbon sequestration, and weaken climate regulation. 
  • Climate change accelerates their spread, making them a threat multiplier that undermines ecosystem resilience and adaptation capacity.

What are the Core Challenges Confronting India in Tackling Invasive Alien Species and the Measures Required?

Conclusion:

Mitigating Invasive Alien Species requires the three I’s – strong Institutions for enforcement, Integration with biodiversity–climate strategies, and Involvement of communities for sustainable action. Together, these pillars can balance ecological resilience with economic growth.