Genetically modified mosquitoes released in the US
The biotech firm Oxitec has released its genetically modified mosquitoes in the Florida Keys with the goal of suppressing wild, disease-carrying mosquito populations in the region. This is the first time genetically modified mosquitoes have been released in the US. Oxitec previously released its modified Aedes aegypti mosquitoes in Brazil, the Cayman Islands, Panama and Malaysia, and the company reported that local A. aegypti populations fell by at least 90 per cent in those locations. A. aegypti can carry diseases such as Zika, dengue, chikungunya and yellow fever, and releasing modified mosquitoes offers a way to control the population without using pesticides. Oxitec’s modified mosquitoes, all male, have been engineered to carry a lethal gene; when the modified pests mate with wild female mosquitoes, the lethal gene gets passed to their offspring. Though the gene does not affect the males’ survival, it prevents female offspring from building an essential protein, and thus causes them to die before reaching maturity. Only female mosquitoes bite people – male mosquitoes exclusively drink nectar – so the modified mosquitoes and their surviving male offspring can’t pass diseases to humans. A. aegypti mosquitoes make up about four per cent of the mosquitoes in the Florida Keys, but cause the vast majority of mosquitoborne disease transmitted to humans in the area. The Florida Keys Mosquito Control District (FKMCD) board typically budgets $1 million (£710,000) a year to control the pest, resorting to costly measures such as spraying aerial insecticides. Releasing hundreds of millions of genetically modified mosquitoes may be a less expensive and more effective option, the board concluded, especially as mosquito populations become resistant to pesticides over time. FKMCD first approached Oxitec in 2010, and after a decade of regulatory assessments and local pushback, both the board and the US Environmental Protection Agency (EPA) finally approved the plan to release the genetically modified mosquitoes in the Keys. In late April 2021 the company placed boxes of mosquito eggs at six locations in Cudjoe Key, Ramrod Key and Vaca Key. Over the preceding 12 weeks, about 12,000 newly hatched male mosquitoes should emerge from the boxes each week. This release will serve as an initial trial so that Oxitec can collect data before running a second trial with nearly 20 million mosquitoes later this year. The company will capture mosquitoes throughout the trial to observe how far the insects travel from their boxes, how long they live and whether female mosquitoes are actually picking up the lethal gene and dying off. To make it easier to track the modified mosquitoes, Oxitec also introduced a gene that causes the mosquitoes to glow under a specific colour of light.
“Modified mosquitoes and surviving male offspring can’t pass diseases to humans”