Is genetic engineering the right way to cure the problem of invasive species?

A new gene-based technology allows curbing the population of species such as mosquitoes which spread malaria or dengue. But there are dangers involved

By Aditya Misra
Published: Tuesday 22 July 2014

Malaria-carrying mosquitoes which kill hundreds of thousands of people in Asia and Africa are some of the species that need to be controlled urgently  Invasive species are those which find a foothold in a foreign environment and multiply to the extent that they become a threat to native species.  They, sometimes, are also carriers of diseases. But a new technology has given a tool to deal with the problem.

A paper published on July 17 in the journals Science and eLife, discusses RNA-guided gene drives based on CRISPR (clustered regularly interspaced short palindromic repeats) technology. The technology allows scientists to target and alter specific genes towards a desired result. For example, tilting the sex ratio of a certain species towards its male offspring would cause a fall in the population. Similar results can be achieved by lowering a species’ fertility or by reducing its resistance to a pesticide. These genes would be passed on to the next generation when the species breeds, causing it to eventually become extinct.

There is no end to the number of invasive species it can be used against. Malaria-carrying mosquitoes which kill hundreds of thousands people in Africa and India every year are one such target. The Asian tiger mosquitoes, which have spread beyond their native zone of south east Asia, and spread many virus including dengue and Japanese encephalitis, are another. Another could be the Argentine ants, which belong to South America but are now found in five continents, competing with native ant species.

But such “gene drives” have their own dangers, say media reports. If the species breeds with a native, the harmful trait can get transferred. There is also the possibility of the gene evolving into something different and unpredictable. Also, if the invasive species transfers the gene to its native region making the population dwindle, it could be dangerous as the role of the species in its native area could be crucial for that ecosystem.

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