Released genetically modified mosquitoes spread - risk unexplained

Gene experiment fails ominously

A failed experiment in genetically modifying mosquitoes could have dangerous effects on humans. Instead of fighting mosquito-borne diseases, an insect strain was modified to contain a dominant deadly gene that was supposed to prevent mosquito reproduction. However, these seem to have become more resistant after a short time and the number of insects is increasing strongly again.

In an experiment on mosquitoes, the researchers have now created insects that carry a dominant, deadly gene in order to limit reproduction. However, this only works for a short time. A report by Yale University on the failed experiment was published in the English-language journal "Scientific Reports".

What was the aim of the experiment?

In the experiment, the researchers wanted to genetically modify mosquitoes (mosquitoes) so that the insects had fewer offspring, which would reduce the population size. This experiment seems to have failed because the genes of the modified mosquitoes mix with the native population of insects, which shouldn't be possible.

Population of mosquitoes was only declining

When trying to control mosquito-borne diseases such as yellow fever, dengue, chikungunya and zika fever, a mosquito strain was genetically modified. In Brazil, approximately 450,000 males of the genetically modified strain were released weekly for a period of 27 months. As a result, the number of insects initially decreased, but after 18 months the number of mosquitoes began to increase again.

The trial may have made insects even more resistant

The real idea was that genes from the release strain would not get into the general population of insects because their offspring would die. But then the situation developed completely differently. It is even feared that the experiment could have made the mosquitoes more resistant. However, the public was informed that the insects pose no additional health risk.

How important is a genetic monitoring program?

Analysis of the experiment indicated that the effectiveness of the release program waned after about 18 months, after which the mosquito population almost recovered to the number it had before the test. These results show how important it is to implement a genetic monitoring program during the release of transgenic organisms to identify unforeseen consequences. The modified mosquito strain was developed by a company that had previously received FDA approval for similar tests. (as)

Author and source information

This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.


  • Benjamin R. Evans, Panayiota Kotsakiozi, Andre Luis Costa-da-Silva, Rafaella Sayuri Ioshino, Luiza Garziera et al .: Transgenic Aedes aegypti Mosquitoes Transfer Genes into a Natural Population, in Scientific Reports (query: 18.09.2019), Scientific Reports

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