Invasive Alien Species in India: Threats and Management (UPSC Environment)

Invasive Alien Species (IAS) are plants, animals or microorganisms introduced — accidentally or deliberately — outside their native range, that establish themselves, spread and cause harm to biodiversity, ecosystems, human livelihoods or the economy. The key qualifier is that they spread and sustain without human assistance, outcompeting native species.

The IPBES Thematic Assessment on Invasive Alien Species (2023) ranked IAS among the top five direct drivers of global biodiversity loss — alongside land-use change, climate change, pollution and overexploitation. Globally, over 37,000 alien species have been introduced by humans; more than 3,500 are recognised invasive. The annual economic cost is estimated at $423 billion globally.

In India, IAS cause environmental and economic damage estimated in trillions of rupees. They push native species to decline, degrade ecosystems, fuel human-wildlife conflict, damage crops and undermine sustainable livelihoods.

Key Definitions

• Alien species: introduced outside its native range.
• Invasive alien species: alien species that spread and cause harm.
• Naturalised species: alien species that establish self-sustaining populations but do not necessarily harm natives.

The line between naturalised and invasive is thin. Many species sit there for decades before exploding into invasiveness when a trigger — climate change, land disturbance — arrives.

Major IAS in India

Plants

• Lantana camara — ornamental from Central America; now invades 40% of India's tiger reserves.
• Prosopis juliflora (Vilayati babul / Mesquite) — introduced in 1870s for fuelwood; invades arid Rajasthan, Gujarat, Tamil Nadu, Andhra Pradesh.
• Parthenium hysterophorus (Congress grass / Gajar ghas) — came with US wheat aid in 1950s.
• Eichhornia crassipes (water hyacinth) — clogs wetlands and water bodies.
• Mikania micrantha (mile-a-minute weed) — severe in Northeast forests.
• Ageratum conyzoides.
• Chromolaena odorata (Siam weed).

Animals

• African catfish (Clarias gariepinus) — banned, but persists in Indian waters.
• Suckermouth catfish / plecos (Pterygoplichthys).
• Red-eared slider turtle — popular pet now in Delhi and Kolkata water bodies.
• Giant African snail.
• Golden apple snail (rice fields in Kerala).
• Argentine ant, red imported fire ant.

Microbes and Pathogens

• Phytophthora infestans (potato late blight).
• Banana bunchy top virus.

Reasons for Spread in India

Weak Biosecurity

India does not have a dedicated national biosecurity law covering all IAS pathways. Plant Quarantine, Animal Quarantine and Livestock Importation rules exist in silos. There is no single authority authorised to regulate movement and manage IAS across sectors.

Agency Coordination Gaps

Even within MoEFCC, databases conflict. The National Biodiversity Authority and Botanical Survey of India have identified different numbers of invasive species — 63 vs 173 in one comparison — reflecting the absence of a standardised framework for designating a species as invasive.

Awareness Deficit

Most people, government officials included, do not distinguish between alien, naturalised and invasive. Ornamental alien species (Lantana, duranta, water hyacinth) remain popular in gardens and ponds.

Perverse Incentives

Some IAS are actively used for livelihoods. Lantana camara — on the IUCN list of world's 100 worst invasive species — is woven into handicrafts by tribal cooperatives. Prosopis juliflora provides charcoal and fuelwood to landless households. NGOs and welfare schemes sometimes promote their exploitation in the name of poverty alleviation.

While this looks like a management strategy — "use them up" — scientific evidence that commercial harvesting reduces IAS populations is thin. In fact, monetary incentives create community dependence, stable markets and fresh invasion incentives.

Legal Vacuum

No legal framework holds any person or organisation liable for unintended impacts caused by the IAS they introduce. Aquariums, horticulture, pet trade and accidental shipping introductions are effectively unregulated.

Positive Feedback Loop

When utility value is recognised, more IAS get promoted on the same logic. By the time long-term ecological damage is apparent, the damage is done and the market resists policy correction.

What Makes IAS So Successful

• Escape from natural enemies: predators, pathogens and competitors from native range do not come along.
• High reproductive output — seeds in the millions, rapid maturation, hermaphroditism.
• Efficient dispersal — wind, water, hitchhiking on humans.
• Generalist ecology — broad diet, wide climatic tolerance.
• Allelopathy — chemicals that suppress native plants (Parthenium, Lantana).
• Disturbance affinity — thrive on disturbed, degraded or fragmented ecosystems.
• Climate change synergy — warmer temperatures and extreme events open new habitat.

Impacts

• Biodiversity loss — native species decline or disappear.
• Ecosystem services collapse — pollination, soil fertility, water quality.
• Agricultural losses — weeds and pests reduce yield.
• Human health — pollen allergies (Parthenium), vector spread.
• Fire risk — Lantana creates continuous fuel beds in forests.
• Human-wildlife conflict — native herbivores lose forage; push into farms.
• Water body degradation — water hyacinth chokes wetlands.

Global and Indian Framework

International

• Convention on Biological Diversity (CBD), Article 8(h) — parties commit to prevent, control or eradicate IAS.
• Kunming–Montreal GBF Target 6 (2022) — reduce rate of introduction and establishment of invasive alien species by at least 50% by 2030.
• IPBES Assessment 2023 — comprehensive scientific baseline.
• International Plant Protection Convention (IPPC) — plant quarantine standards.

India

• Wildlife Protection Act 1972 — regulates species but IAS are not uniformly addressed.
• Biological Diversity Act 2002 — National Biodiversity Authority, State Biodiversity Boards.
• Plant Quarantine Order 2003, Livestock Importation Act 1898.
• Forest (Conservation) Act 1980 — indirect.
• Coastal Regulation Zone notifications.

Management Approaches

• Prevention — strict quarantine at ports, airports, borders; e-surveillance.
• Early detection and rapid response.
• Mechanical removal — Lantana uprooting campaigns in tiger reserves.
• Chemical control — targeted herbicides (limited in PAs).
• Biological control — natural enemies released with extreme caution.
• Use and restoration — replace invasive-dominated landscape with native species.
• Community engagement — tribal cooperatives but with caution against perverse incentives.

Way Forward

• National Biosecurity Act covering all pathways — agriculture, horticulture, aquaculture, pet trade, shipping.
• Unified national IAS list with clear criteria.
• Landscape-scale restoration programmes, especially in tiger reserves and Himalayan forests.
• Horizon scanning for emerging IAS under climate change.
• Polluter/introducer liability principle.
• Public awareness and ban on sale of top invasive ornamentals.
• Research funding via ICAR, ICFRE, WII, ZSI, BSI.

Latest Developments (2024–26)

Updated context:

• IPBES IAS Assessment (Sep 2023) is the most authoritative recent synthesis — flagged by India as a policy driver.
• India's draft National Biosecurity Framework (2024) is under inter-ministerial consultation.
• Amrit Dharohar and Mishti indirectly help manage wetland and mangrove IAS.
• Lantana removal drives in Kanha, Bandhavgarh, Corbett and Bandipur expanded in 2024–25 under state forest departments.
• National Biodiversity Strategy and Action Plan (NBSAP) update (2024) aligns with GBF Target 6.
• Research by IISc, WII and NCBS (2023–24) mapped Lantana invasion across 45% of Indian forest area.
• MoEFCC advisory 2024 bans specific ornamental aliens from government procurement.

UPSC Relevance

Paper mapping: GS Paper III — Environment, Biodiversity; GS Paper II — Governance, Biosecurity.

Prelims pointers:

• CBD Article 8(h) addresses invasive alien species.
• The IPBES Assessment on IAS was released in September 2023.
• Kunming-Montreal GBF Target 6 targets 50% reduction in IAS introduction rate by 2030.
• Lantana camara is in IUCN's 100 worst invasive species list.
• Prosopis juliflora was introduced in the 1870s for fuelwood.
• Parthenium entered India through US wheat aid (PL-480) in the 1950s.
• Mikania micrantha severely affects Northeast forests.
• National Biodiversity Authority is based in Chennai.

Mains angles:

• "Discuss how invasive alien species threaten India's biodiversity and suggest an integrated management framework."
• "Examine the role of invasive alien species in human-wildlife conflict and ecosystem degradation in India."