Plagued by “skeeters” this summer? Scientists say they’ve nearly eliminated disease-carrying mosquitoes on two islands in China. But the downside of their new technique may be impracticality—and expense.
Researchers targeted a species of white-striped bug that spreads dengue fever, Zika, and other diseases. They infected the bugs with a virus-fighting bacterium, then zapped them with a small dose of radiation.
In 2016 and 2017, a team led by Zhiyong Xi at Michigan State University released infected and zapped male mosquitoes onto two small islands near Guangzhou, China. The number of female mosquitoes responsible for disease spread plummeted by 83-94% each year. The results were similar to other methods like spraying insecticides and using genetically altered mosquitoes. Some weeks, researchers found no signs of disease-carrying mosquitoes. Xi says no technique so far has had that kind of success.
The problem was that the method required swarming the islands with up to four million mosquitoes each week. Over the two years, the number totaled around 200 million mosquitoes released.
The number of bugs needed for the small islands—the largest of which was only three times the size of New York’s Central Park—concerns Scott O’Neill of the World Mosquito Program. “It’s hard for me to see how this can be scaled up,” he says.
Biologist Brian Lovett has another concern. He says the method must be ongoing: “If you don’t keep doing it, then populations can fairly quickly reestablish.”
That’s exactly what happened in the experiment: Mosquitoes either buzzed in from elsewhere or matured from young larvae.
Lovett says the new mosquito method would require constant monitoring and probably a lot of money—for all that infecting, zapping, and transporting.
Researchers believe costs will go down as the technology advances. Costs may end up being about the same as some methods. The new technique could even be cheaper than certain insecticides—which mosquitoes are increasingly becoming resistant to. For now, keep swatting!
(This July 13, 2019, photo shows mosquitoes in a container at a lab in Guangzhou, China. Guangzhou Wolbaki Biotech via AP)
