Oct. 31, 2022 -- The number of disease-carrying mosquitoes in a Brazilian city dropped by up to 96% after hundreds of genetically modified male mosquitoes were released, New Scientist reported.
The U.K. biotech company Oxitec is releasing these male mosquitoes in other locations of the world to control illnesses that mosquitoes spread, such as dengue, malaria, and Zika.
The male mosquitoes, which don’t bite humans, are genetically modified to transmit a gene to female offspring that causes them to die before they can reproduce and spread illness.
The latest test took place in Indaiatuba in the state of São Paulo when hundreds of males were released from May 2018 to April 2019, New Scientist reported.
The number of mosquitoes in the places where the modified mosquitoes were released dropped by 88% to 96% from November 2018 to April 2019, the peak breeding season, compared to communities where no release occurred, New Scientist said.
Using mosquito traps, researchers discovered that the engineered gene was found in about half the surviving male offspring of the modified mosquitoes, New Scientist said. After six months or so, the gene disappeared.
“It was exactly what we expected,” Nathan Rose, head of Oxitec’s malaria program, told New Scientist. “We knew that [the gene] would continue for a little while, but we expected it to disappear.”
The testing did not determine if the spread of diseases decreased, only if the reproduction of mosquitoes dropped.
However, similar studies that didn’t involve Oxitec reported significant reductions in the number of dengue cases found in Indonesia and Australia after the introduction of genetically modified male mosquitoes, New Scientist said.