Invasive alien species

Story hook

In 1809, a few specimens of an ornamental shrub from the West Indies were planted in the Royal Botanical Gardens, Calcutta. The plant had brilliant clusters of pink-yellow-orange flowers and was rumoured to repel mosquitoes. By the 1840s, it had escaped the garden. Today, Lantana camara covers 40 % of India's tiger habitat (~ 1.5 lakh sq km), suppresses native grass and shrub regeneration, makes the forest impenetrable to herbivores, and is the leading cause of habitat degradation in Bandipur, Nagarhole, Mudumalai, and Wayanad.

Now flip the frame. In a 2024 Nature paper, ecologists estimated that invasive alien species cost the world $423 billion per year — more than the GDP of Norway. The 2023 IPBES Invasive Alien Species Assessment — the first global stocktake — found that 37,000 alien species have been introduced to new ecosystems, of which 3,500 are invasive and harmful. India alone has 2,000+ alien species, of which 173 are seriously invasive (Botanical Survey of India inventory).

This file is about that quiet conquest — Lantana in our forests, Prosopis in our deserts, African catfish in our rivers — and the institutional response: the Guidelines for Listing of Alien Species (GLAS, 2022), the Wildlife Protection (Amendment) Act 2022, and the Convention on Biological Diversity Aichi Target 9.

Why this matters for UPSC

Invasive Alien Species (IAS) is the second largest cause of biodiversity loss globally (after habitat destruction), per IPBES 2023. UPSC has asked about IAS in at least 3 Prelims years since 2018 (Lantana, water hyacinth, African apple snail) and Mains questions have explicitly cited GLAS and the IPBES report. Interview boards in Karnataka, Tamil Nadu, Rajasthan probe candidates.