Invasive alien species in India

Not every non-native species is a problem. Many crops, from potatoes to tomatoes, came from elsewhere and are now part of Indian farming. A species becomes invasive when it is introduced — deliberately or accidentally — outside its natural range, establishes itself, spreads, and causes harm to native species, ecosystems, livelihoods or health. The harm, not the foreign origin, is the test.

In India, well-known examples include lantana, which spreads through forests and grasslands and changes fire and grazing patterns; water hyacinth, which chokes lakes and canals, blocks light and oxygen, and hampers fishing and navigation; and Prosopis juliflora, introduced in places for fuel and shade, which in some arid areas competes aggressively with native vegetation and groundwater. Parthenium, a weed, affects crops and can cause skin and respiratory problems in people who handle it. Each case is local: a plant that is useful in one setting can be a pest in another.

Control is difficult and expensive once a species is widespread. Prevention — checking imports, ballast water, nursery stock and aquarium or pet releases — is cheaper than eradication, and early detection with rapid removal works better than a campaign launched after a species has covered a district. Biological control, using a natural enemy, can help but carries its own risk if the control agent itself spreads, so it needs careful testing and regulation.

Globally, the Kunming-Montreal framework adopted in 2022 sets a target of reducing the introduction and establishment of invasive alien species by at least 50 per cent by 2030. India has no single comprehensive invasive-species law; control is spread across forest, agriculture, quarantine and customs rules. That fragmentation is itself a policy problem for students to notice. It also means that a trader, a farmer and a forest officer may each follow a different rulebook for the same species, which weakens prevention.