A British company Oxitec has lodged an application with the Australian Gene Technology Regulator to approve the release of genetically altered mosquitos. Aedes aegypti mosquitoes carry dengue and yellow fever. These mosquitoes live in tropical and subtropical areas and can be found in northern parts of Australia. Climate change warming is predicted to extend their range south.
The genetically altered mosquitoes will have two DNA tweaks. The first will create female larvae that die before they reach adulthood and are able to breed. The second will create a red fluorescent marker so that the mosquitoes can be easily identified. When the modified males mate with wild females, the resultant female larvae die. The male larvae will survive to pass on the gene to the next generation. Since the females are the ones that bite and pass on disease, it is hoped that the number of disease carrying mosquitoes will be drastically reduced.
To stop the gene being passed into wild populations ad infinitum, the gene is designed to be inherited by male mosquitoes only. This means that each generation halves the number of mosquitoes carrying the modified genes and the gene eventually dies out and more modified mosquitoes have to be imported to continue the cycle.
There is some controversy about the method. In the USA, some communities have voted to reject trials using modified mosquitoes. In Australia, the Torres Islands are proposed as the first trials. Oxitec and the CSIRO are also working on population control of the Asian tiger mosquito, another invasive species which carries disease.
Reference: The Sydney Morning Herald, Tuesday, December 10, 2024 page 16.
Predicted spread of Aedes aegypti mosquitoes.