The Hindu Business Line : `Aliens can eat into world's food supply'

ALIEN is no sci-fi stuff, but a real threat to biodiversity, according to a recent update from World Bank. The alert is not about men from Mars or women from Venus but "invasive plants, animals and other organisms" that put the world's food supply to risk.

These invasive species, ranging from microbes to mammals, are non-native to the ecosystem, and hence the name `alien'. Though human actions are responsible for the problem, recognition of the same is new.

And alien species are on the rise, becoming "more severe through climate change".

Introduction of aliens can ham human health, and also economically and environmentally, informs www.invasivespecies.gov. So does warn the World Bank too: "After being brought into an area, the alien species will take over and crowd out native species, leading to adverse impacts both on agriculture and biodiversity."

According to the Bank's lead biodiversity specialist, Dr Kathy MacKinnon, harm would be visible as reduced crop yields, choked irrigation canals, blocked hydroelectric dams and a cut in the lifespan of development investments, thus constraining poverty alleviation and food security.

There are alarming numbers in the update about the economic cost of aliens. For India, "the cost is put at more than $100 billion dollars a year", while Brazil's estimates are $50 billion, and South Africa loses $7 billion in production. Examples of this costly menace are: Soyabean rust in Brazil, cassava mealy bug and green mite taking a toll on crops up to 80 per cent, and American Atlantic jellyfish contributing to "lost fisheries revenue in the Black Sea".

Strangely, many aliens were invited as friends, "introduced to a country by people with good motives", though the results have proved to be disastrous. MacKinnon cites the example of the Golden Apple snail, "the most devastating" among aliens. "It was imported from Latin America to South East Asia in the 1980s."

Its initial attractions as food source lay in high protein content, and the ability to breed fast; but it escaped to wreak havoc as a serious pest to rice. Worldwide losses because of this slimy snail are pegged at $250 billion a year.

Similar is the case of the water hyacinth, originally a native of the Amazon Basin, and now a global nuisance, though with a `showy purple flower'. It is notorious for affecting water flow, hampering electricity generation, and standing in the way of transport, water quality and indigenous biodiversity.

One country's emblem can be another's problem, if you're talking of wattle, Australia's flower. "Wattle and other trees are taking over the mountain catchments areas surrounding Cape Town in South Africa, and, if they continue at current rates, could reduce water supply for the city by 30 per cent."

So, there is now a `Working for Water' programme to eradicate the problem.

"The $100 million a year programme involves hiring unskilled labour from local townships who are armed with chainsaws to cut down the trees - therefore generating local employment," informs the update.

This was found to be cheaper than to build new dams.

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