Living with aliens


How can we live with aliens? Of course, I mean alien invasive species that have spread themselves around the world hitchhiking our transport systems. Indeed, many of them have travelled far along our shipping routes. Zebra mussel is a classic example of an alien species that travelled from the Black Sea to the Great Lakes in North America in 1988. It soon became invasive in its new home and proliferated so much that it started to clog water pipes. At one point, this invasion by the alien was reported to cut off a town’s water supply!

I was at the University of Oxford Botanic Garden the other day giving a public lecture ‘A brave new world: Alien invasive species and novel ecosystems’. This was to celebrate the International Day of Biological Diversity. I talked about the example of Lantana (pictured above), one of 10 worst invasive species in the world. I find Lantana an absolutely admirable weed! It is a native of South America from where it was introduced in the 1800s to botanical gardens in British colonies. It really thrived in Australia, India and South Africa and after two centuries it now occupies land area as big as England on the Indian subcontinent, nearly as big as Scotland in Australia, and bigger than Wales in South Africa.

There are hundreds of other species – plants and animals – that join Lantana’s league as alien invasives. They are everywhere – on land, in water and in the sea. We have tried everything to get rid of these species, but they have kept spreading. In 2009, the cost of Lantana eradication in India was estimated to be $200 per hectare. We know that Lantana is spread over 13 million hectares in India, so the total cost of Lantana eradication – if India decides to eradicate it – will come to $2.6 billion. This sum is bigger than the gross domestic product (GDP) of Maldives! The cost of eradicating Lantana in Australia and South Africa is as high if not higher and there is no guarantee that once eradicated Lantana will not return. Can we ever afford or justify spending that sort of money on eradication of alien invasive species?

If we can’t afford to eradicate them, how can we live with them? Think of Lantana. It has spread over 20 million hectares just in Australia, India and South Africa. That makes it an abundant resource. Now think of tropical forests that are sacrificed to supply wood and paper  to meet our needs. Could we use Lantana instead? That will solve the problem of Lantana invasion and deforestation – two birds in one stone! Eating invasive species also sounds like a compelling solution. In his book Jackson Landers reports his adventures of hunting, cooking and eating invasive alien species in North America. There are many other people who have now started to look seriously at invasive species as a source of food.

So, can we address food insecurity in some parts of the world by promoting invasive species as food more widely? A report by the Food and Agriculture Organisation of the United Nations has concluded: “Eating more insects could help fight world hunger“. Of course, not all insects are invasive, but they are abundant and can provide food in much more ‘environmentally-sustainable’ manner than cattle and poultry. Arguably, that leaves out the vegetarians among us, but there are always plenty of weeds for us to eat!

Ralph Waldo Emerson (1803-1882), who led the Transcendentalist movement in the mid-19th century America, once said: “What is a weed? A plant whose virtues have not yet been discovered.” That, to me, sounds like a good approach to living with aliens.


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