Explain the concept of invasive alien species with examples from both flora and fauna in India. Analyze the implications of their spread and outline strategies to mitigate these risks.


The Andaman and Nicobar Islands administration has requested help from the Wildlife Institute of India to manage the invasive chital population on Ross Island, threatening the local ecosystem.


  • Introduce your answer by deefining invasive alien species (IAS) and their impact on biodiversity and ecosystems.
  • In the main body, list examples of IAS in India from both flora and fauna, discuss their ecological and economic implications, and mention strategies for their management and mitigation.
  • Conclude by emphasizing the urgency of addressing IAS to preserve India’s biodiversity.


Invasive alien species (IAS), as defined by the Convention on Biological Diversity (CBD), are organisms that threaten biological diversity when introduced outside their natural distribution. These species, which include animals, plants, fungi, and microorganisms, often follow the pattern of “arrive, survive, and thrive,” impacting ecosystems by competing with native species for resources. According to IPBES report, around 37,000 such species have been established globally, with about 200 new introductions annually.

Examples of Invasive Alien Species in India:

  • Flora:
    • Lantana camara: A fast-growing shrub, it outcompetes native vegetation and forms dense thickets, hindering regeneration.
    • Parthenium hysterophorus (Congress weed): This weed aggressively invades grasslands and agricultural fields, reducing crop yields.
    • 173 species of invasive plants such as Cassia Uniflora, Prosopis Juliflora, Needle bush, Black Wattle, Goat weed, Prickly poppy, Black mimosa, Water hyacinth etc. are found in India.
  • Fauna:
    • Chital (Spotted deer): Introduced to the Andamans, they lack predators and overgraze, impacting native flora.
    • African catfish: Introduced for aquaculture, it preys on native fish species, disrupting food chains.
    • Papaya Mealy Bug affecting papaya crops in Assam and West Bengal.
    • Zoological survey of India has made a list of 157 invasive alien species out of which 58 are found on land and freshwater and 99 are found in marine ecosystem.

Implications of the Spread of Invasive Alien Species

  • Biodiversity Loss: Invasive species compete with native species for essential resources such as light, water, space, and nutrients, often with more efficiency, leading to a decline in biodiversity. This can disrupt ecological balances, altering habitat structures and food webs.
    • The invasive Nile tilapia competes aggressively with native fish species.
  • Economic Damage: Invasive species can cause considerable economic losses in agriculture, forestry and fisheries by reducing crop yields, destroying crops, and increasing the costs of control and management.
    • The cotton mealy bug has caused extensive damage to cotton crops in India.
    • The global economic cost of IAS was over $423 billion annually in 2019.
  • Health Implications: Some invasive species are vectors for new diseases or create breeding grounds for disease vectors, thereby posing health risks to humans and livestock.
    • The proliferation of the Aedes mosquito due to unchecked growth of invasive plant species in stagnant water bodies has been linked to outbreaks of dengue and chikungunya.
  • Environmental Degradation: Invasive species can alter the physical environment, such as changing soil composition and water availability.
    • Prosopis juliflora has spread across arid and semi-arid regions of India, affecting the local water table and soil salinity.
  • Alteration of Fire Regimes: Some invasive plant species are highly flammable and can change the frequency and intensity of wildfires, which can alter ecosystems and endanger species adapted to historical fire regimes.
    • Invasive buffel grass helped fuel the deadly Maui fires (Hawaii) in 2023.

Strategies to Mitigate Risks from Invasive Alien Species:

  • Preventive Measures: This includes stringent biosecurity measures at borders and within the country to prevent accidental or intentional introductions.
    • Enforcing strict quarantine laws.
  • Early Detection and Rapid Response Systems: The creation of a national invasive species database and alert system that enables quick sharing of information to eradicate or contain invasive species.
    • The National Invasive Species Information Center (NISIC).
  • Integrated Management Approaches: Using a combination of mechanical, chemical, and biological control methods tailored to specific environments and invasive species.
  • Legislative and Policy Frameworks: Amending the Wildlife Protection Act to include species within India which might be invasive to a particular region under invasive species definition and stricter penalties.
  • Habitat Restoration: Restoring native habitats can help native species to rebound and compete more effectively against invasive species.
  • Public Awareness:Educating citizens on the dangers of IAS and promoting responsible pet ownership.
  • Supporting Research: into the ecology of invasive species and the effectiveness of control measures can lead to more effective management strategies.

Invasive alien species pose a serious threat to India’s rich biodiversity. By implementing a multi-pronged approach that includes prevention, control, and awareness campaigns, India can effectively mitigate the risks associated with IAS and protect its natural heritage.

‘+1’ Value Addition:

  • The Ministry of Environment, Forest and Climate Change (MoEFCC) launched the National Action Plan on Invasive Alien Species. It focuses on the prevention, early detection, control, and management of invasive species.
  • Kunming-Montreal Global Biodiversity Framework (2022): Governments have committed to reducing the rate of introduction and establishment of invasive alien species by at least 50% by 2030.
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