The Brazilian city of Piracicaba is expanding the use of genetically engineered mosquitoes to control mosquito borne diseases, including zika and dengue.
It is the first city to trial the mosquitoes, which cause insect populations to crash by passing on a gene that causes offspring to die when they mate with wild insects.
The mosquitoes are produced by the British company Oxitec.
The Aedes aegypti mosquitoes are the main carrier of zika, dengue fever and chikungunya.
The program was approved by Brazil’s National Biosafety Committee (CTNBio) and began in April 2015.
"By the end of the calendar year, results had already indicated a reduction in wild mosquito larvae by 82%," the company said in a statement.
The program has been extended for another year.
Like many invasive insect species, Ae. aegypti’s territory is expanding. Brazil has the highest reported incidence of dengue in the Western Hemisphere, with both chikungunya and Zika virus having entered the country in 2014 and 2015 respectively.
Geneticists have broadly welcomed the program.
"The biological basis of this biological control strategy is well understood and similar strategies have been used for decades for insects mainly of agricultural significance," Dr. David O’Brochta, Professor of Entomology of University of Maryland, was quoted on the Genetic Experts webpage as saying.
He said the move was "generally an encouraging sign that this and related genetics-based technologies for the control or local elimination of mosquitoes is moving towards the mainstream".
Dr. Heidi E. Brown, of the University of Arizona, also welcomed the move, but said it is an intense operation. "These modified, competing mosquitoes will need to continue to be released in order to keep the wild type population down," she said.
Bill Condie is a science journalist based in Adelaide, Australia.
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