Scientists overseeing a population of genetically modified mosquitoes released in Brazil to curb indigenous pathogenic pests say the plan seems to have had the opposite effect, rather new generations of harder, hybrid offspring.
The study led by a Yale University team that collaborated with researchers from Brazil, investigated the impact of transgenic Aedes aegypti mosquitoes developed by the British biotech company Oxitec.
In the course of about two years, Oxitec released tens of millions of its genetically modified insects in the city of Jacobina.
If everything went according to plan, these new male mosquitoes would produce couples with native females and non-viable offspring, reducing the population over time. But the researchers say it didn't happen.
The Yale study found that Jacobina is now home to "a mix of three populations" as a result of the release – and the hybrids seem "sufficiently robust to be able to reproduce in nature."
However, Oxitec has reduced the findings and claims such as & # 39; false, misleading and speculative & # 39; slammed, arguing that the possibility of mixing the modified mosquito genes with the local population has been a concern from the outset, and that this & # 39; self-limiting & # 39; genes do not spread in the wild.
Scientists following genetically modified mosquitoes released in Brazil to curb indigenous pests say the plan seems to have had the opposite effect, rather new generations of harder, hybrid offspring. However, the company behind the project has hit back. Stock image
An Oxitec spokesperson told Dailymail.com that the company has filed an official complaint with Nature in response to the & # 39; inaccurate & # 39; report.
The controversy comes after the biotech company released about 450,000 genetically modified mosquitoes in Jacobina every week for 27 months as part of a plan to combat mosquito-borne diseases, including yellow fever, dengue fever, chikungunya and Zika.
"The claim was that genes from the release strain would not enter the general population because their offspring would die," said senior author Jeffrey Powell, professor of ecology and evolutionary biology at Yale.
"That was clearly not what happened."
In the new study published in the scientific journal Scientific Reports, researchers performed genetic sampling for both the modified and target strains prior to the introduction of the new population, and again six, 12 and 27 months thereafter.
And according to the team, they found & # 39; clear evidence that parts of the transgenic stem genome are included in the target population & # 39 ;.
Or, in other words, the genetically modified mosquitoes that in some cases were not supposed to produce viable offspring did exactly that.
WHAT IS THE AEDES AEGYPTI MOSQUITO?
The Aedes aegypti has white markings on its legs and a mark in the form of a winch on the upper surface of its thorax.
The mosquito is native to Africa, but can now be found in tropical and subtropical regions around the world.
Only the female bites for blood, which she needs to mature her eggs.
What is dengue fever?
Dengue fever causes a high fever, severe headache and joint pain.
The disease can develop into haemorrhagic fever where patients bleed more and experience persistent vomiting. If not treated, it can cause shock and death.
What is Zika
Zika consists of mild fever, rash, joint pain and red eyes.
Some babies with Microcephaly, a condition where the head of a baby is much smaller than expected, have been reported in mothers who were infected with the Zika virus during pregnancy.
"Apparently," the report notes, "rare viable hybrid offspring between the release strain and the Jacobina population are sufficiently robust to reproduce in nature."
The consequences now remain uncertain, although Oxitec insists that there are no negative effects associated with the introduction of the new populations.
Oxitec says it has identified several shortcomings in the Nature report, including the authors' point about a new population with increased "hybrid power" that may be more resistant to insecticides.
According to Oxitec, the data in the report itself, together with other literature on this subject, do not support these claims.
The same applies to the claims of the report on the effectiveness of the technique and the subsequent selective mating, says Oxitec, pointing to about a dozen peer-reviewed publications on the subject that it claims the authors & # 39; ignored or selectively referred & # 39; to be.
Anyway, the controversy underscores the need for careful research when it comes to the introduction of genetically modified organisms into the wild, showing how easily the technique can cause unintended consequences.
"It's the unexpected outcome that relates," Powell said.
"Based largely on laboratory research, one can predict the likely outcome of the release of transgenic mosquitoes, but genetic studies of the kind that we have done should be done during and after such release to determine if there is anything other than predicted . "
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