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Mosquitoes Modified to Create Only Male Offspring Could Help Eradicate Malaria

Scientists have modified mosquitoes to produce sperm that will only create males, pioneering a fresh approach to eradicating malaria.

In a study published in the journal Nature Communications, scientists from Imperial College London have tested a new genetic method that distorts the sex ratio of Anopheles gambiae mosquitoes, the main transmitters of the malaria parasite, so that the female mosquitoes that bite and pass the disease to humans are no longer produced.

“Malaria is debilitating and often fatal and we need to find new ways of tackling it,” said lead researcher Professor Andrea Crisanti. “We think our innovative approach is a huge step forward. For the very first time, we have been able to inhibit the production of female offspring in the laboratory and this provides a new means to eliminate the disease.”

In the first laboratory tests, the method created a fully fertile mosquito strain that produced 95 percent male offspring.

“What is most promising about our results is that they are self-sustaining,” said Dr. Nikolai Windbichler, also a lead researcher. “Once modified mosquitoes are introduced, males will start to produce mainly sons, and their sons will do the same, so essentially the mosquitoes carry out the work for us.”

The scientists introduced the genetically-modified mosquitoes to five caged wild-type mosquito populations. In four of the five cages, this eliminated the entire population within six generations, because of the lack of females. The hope is that if this could be replicated in the wild, it would ultimately cause the malaria-carrying mosquito population to crash.

This is the first time that scientists have been able to manipulate the sex ratios of mosquito populations. The researchers believe the work paves the way for a pioneering approach to controlling malaria.

Since 2000, increased prevention and control measures have reduced global malaria mortality rates by 42 percent, but the disease remains a prevalent killer, especially in vulnerable sub-Saharan African regions. Malaria control has also been threatened by the spread of insecticide-resistant mosquitoes and malaria parasites resistant to drugs. According to latest estimates by the World Health Organization, over 3.4 billion people are at risk from contracting malaria and an estimated 627,000 people die each year from the disease.

In this new experiment, the scientists inserted a DNA-cutting enzyme called I-PpoI into Anopheles gambiae mosquitoes. In normal reproduction, half of the sperm bear the X chromosome and produce female offspring, while the other half bear the Y chromosome and produce male offspring.

The enzyme that the researchers used works by cutting the DNA of the X chromosome during production of sperm, so that almost no functioning sperm carry the female X chromosome. As a result, almost all of the offspring of the genetically-modified mosquitoes were males.

“The research is still in its early days, but I am really hopeful that this new approach could ultimately lead to a cheap and effective way to eliminate malaria from entire regions,” said co-author Dr. Roberto Galizi. “Our goal is to enable people to live freely without the threat of this deadly disease.”

Read more at:

A synthetic sex ratio distortion system for the control of the human malaria mosquito

6 Comments »

  1. This sounds great! I am sure that there will be no ripple effects as we eliminate a major component in the food chain. I have nothing against technology and science but I wonder, has anyone really thought this through?

  2. ^I agree, probably not a good idea to commit genocide on mosquitoes. Malaria is an easily controlled disease when detected early and given treatment, could be better just to fund medicine for the poor.

  3. I am of the general opinion that this is a potentially dangerous approach. I would feel better if their technique wasn’t capable of completely crashing the population, but simply reduced the female portion of the overall population, so that the food web would be preserved.

    A better approach would seem to be removal of the female’s ability to drink blood. I mean, yes, the females use that to produce offspring, but they are technically capable of producing eggs without blood – just not as many. Some species, like the Elephant mosquito, doesn’t drink blood at all – instead preying on other mosquitoes in the larval stage in order to produce the maximum number of viable offspring. If we removed their ability to drink blood completely it would take a while to spread through the food chain because the females without this gene would produce more offspring, so could just weaken it so they couldn’t drink blood from humans specifically, or maybe even gave them a particular aversion to humans, like an encoded allergy or something. Still, I think that a world where Mosquitoes don’t bite and just pollinate would be beautiful.

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