Scientists at John Hopkins University in Maryland have created a GM mosquito which is resistant to the malaria parasite, meaning that it cannot be carried and transferred to humans via a bite.
The researchers released 1,200 GM mosquitoes into a cage containing mice infected with malaria. The cage also contained normal, non GM mosquitoes. At the end of the experiment, the researchers found that the GM mosquitoes had become the dominant strain, forming 70 per cent of the total population within the cage. Although the GM mosquitoes were physically weaker, they lived longer and laid more eggs because they were free of the malaria parasite.
Genetic modification is now being hailed as the route towards managing the malaria epidemic, in preference to sprays or drugs. The scientists believe that a batch of GM mosquitoes released into the wild would eventually become dominant over their conventional cousins.
But the wide-scale, uncontrolled release of genetically modified organisms into the environment raises serious ecological questions. Jonathan Matthews, editor of GMwatch e-magazine, told the Ecologist that the key unknown was the consequences of wiping out traditional mosquitoes. He said:
‘Whatever the initial advantages of GM mosquitoes, their evolutionary sustainability in the longer term is simply an unknown, and this could have a devastating impact on the food chain.’
He added: ‘Mosquito larvae can be at the base of the food chain for fish, while adult mosquitoes provide food for bats and birds. Mosquitoes are also important pollinators, as plant nectar forms a large part of their diet. So such a major human intervention could have worryingly unpredictable consequences.’
The GM mosquitoes could be released in a African trial within five years.
This article first appeared in the Ecologist March 2007