Scientists in China nearly ELIMINATE disease-carrying mosquitoes from two islands plagued by dengue fever using radical new technique (but some warn it's not the miracle cure it seems)

  • Researchers released male mosquitoes onto two small islands near Guangzhou
  • They targeted Asian tiger mosquitoes, which spread dengue fever and Zika
  • Bugs were infected with virus-fighting bacterium then zapped with radiation
  • Zapping sterilizes them, releasing infected ones stops them from reproducing

Scientists say they nearly eliminated disease-carrying mosquitoes on two islands in China using a new technique. 

The downside: It may not be practical for larger areas and may cost a lot of money.

In the experiment, researchers targeted Asian tiger mosquitoes, invasive white-striped bugs that can spread dengue fever, Zika and other diseases. 

They used a novel approach for pest control: First, they infected the bugs with a virus-fighting bacterium, and then zapped them with a small dose of radiation.

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The photo from Guangzhou Wolbaki Biotech shows male Aedes albopictus mosquitoes in a container at the company's lab in China. Researchers zapped the insects with a small dose of radiation and infected them with a virus-fighting bacterium called Wolbachia

The photo from Guangzhou Wolbaki Biotech shows male Aedes albopictus mosquitoes in a container at the company's lab in China. Researchers zapped the insects with a small dose of radiation and infected them with a virus-fighting bacterium called Wolbachia

Zapping is meant to sterilize the mosquitoes. And releasing mosquitoes infected with a bacterial strain not found in wild mosquitoes would stop them from reproducing. 

Mosquitoes need to have the same type to make young that will survive.

For 18 weeks in 2016 and 2017, the team led by Zhiyong Xi at Michigan State University released male mosquitoes onto two small islands near Guangzhou, China, a region plagued by dengue fever. 

The number of female mosquitoes responsible for disease spread plummeted by 83% to 94% each year, similar to other methods like spraying insecticides and using genetically modified mosquitoes. Some weeks, there were no signs of disease-carrying mosquitoes.

No technique so far has had that kind of success, Xi said.

The problem, though, was that it required swarming the islands with lots of mosquitoes, up to 4 million each week. 

Researchers zapped the insects with a small dose of radiation and infected them with a virus-fighting bacterium called Wolbachia. Males and female mosquitoes with different types of Wolbachia won't have young that survive

Researchers zapped the insects with a small dose of radiation and infected them with a virus-fighting bacterium called Wolbachia. Males and female mosquitoes with different types of Wolbachia won't have young that survive

Males and female mosquitoes with different types of Wolbachia won't have young that survive. So researchers intentionally infect males with a strain not found in the area and then release the insects

Males and female mosquitoes with different types of Wolbachia won't have young that survive. So researchers intentionally infect males with a strain not found in the area and then release the insects

Over the two years, the number totaled to around 200 million mosquitoes released.

The findings appear Wednesday in the journal Nature.

Scott O'Neill of the World Mosquito Program was concerned by the number of bugs needed for even these small islands, the largest of which was three times the size of New York's Central Park.

'It's hard for me to see how this can be scaled up' to help residents, he said in an email.

Biologist Brian Lovett at the University of Maryland in Bethesda said this isn't a once and done process.

'You have to keep doing it. And if you don't keep doing it, then populations can fairly quickly reestablish,' he said.

This July 13, 2019 photo provided by Guangzhou Wolbaki Biotech shows containers where Aedes albopictus mosquito larvae are being raised at the company's lab in Guangzhou, China

This July 13, 2019 photo provided by Guangzhou Wolbaki Biotech shows containers where Aedes albopictus mosquito larvae are being raised at the company's lab in Guangzhou, China

That's exactly what happened in the experiment: Mosquitoes either buzzed in or matured from young larvae to replace those that died. 

It's going to require constant monitoring and, potentially, a lot of money, Lovett said.

Costs will go down as the technology advances, the researchers said. They estimate it could range from $42 to $66 per acre of land per year.

That's on par with agricultural pest sterilization methods and cheaper than some insecticides, which mosquitoes are increasingly becoming resistant to, Xi said.

The team has an ongoing project in an area roughly four times larger than their original sites.

WHY DO MOSQUITOES BITE SOME PEOPLE AND NOT OTHERS?

Around 20 per cent of people are more prone to mosquito bites.

And while scientists are yet to find a cure, they do have some ideas as to why the insects attack some of us more than others.  

Blood type

Certain blood types are more attractive to taste buds of mosquitoes. 

Research has shown that people who have Type O blood - the most common blood type - tend to get bitten twice as much as those with Type A. People with Type B blood get bitten somewhere in the middle. 

Exercise and metabolism

Working up a sweat during exercise can also make a person more susceptible to a mosquitoes bite.

Strenuous exercise causes higher body temperatures and a buildup of lactic acid, which emit yummy signals to the insects.     

Beer    

A cold glass of beer makes you sweat and your body release ethanol, which may be why mosquitoes like to land on beer drinkers. 

Skin bacteria 

Levels of bacteria on the human skin can entice mosquitoes to bite, particularly where bacteria clusters like on the ankles and feet. 

Having different types of bacteria on the skin, however, tends to turn the insects off. 

Body odour 

Mosquitoes use even the faintest of human body odours when searching for potential victims.

It’s been known for some time that female mosquitoes use specific sensors around their mouths to detect carbon dioxide being exhaled from humans and animals.

But a few years ago, researchers from the University of California Riverside discovered the blood-sucking insects also use these same sensors to detect body odours - especially the smell of feet. 

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