Mosquitoes may be small, but they are a pretty big problem when it comes to public health in many areas of the globe. Now, a Chinese ‘mosquito factory’ is doing something about it that may become a widespread practice: releasing millions of male mosquitoes each week so they can breed with wild female mosquitoes and eventually kill off the species. How will that work, exactly? The mosquitoes they release will be infected with a bacteria that results in infertile eggs in female offspring, so after a few generations, the numbers will fall dramatically.
On Monday, March 14, a team of researchers led by Zhiyong Xi of China’s Sun Yat-sen University and Michigan State University’s Joint Center of Vector Control for Tropical Diseases announced they will begin releasing male mosquitoes intentionally infected with Wolbachia bacteria. When those mosquitoes mate with wild females, the eggs in female offspring will be infertile, greatly reducing reproduction rates. The bacteria is passed on from generation to generation, making it a long-term strategy for reducing the numbers of disease-carrying mosquitoes in regions where the infected males are released.
This approach to disease control may seem radical, but many scientists feel it is an effective means to drastic reductions in risk of a variety of mosquito-borne illnesses, including malaria, dengue fever, yellow fever, and the Zika virus. The ‘factory’ is planning to release up to 20 million infected mosquitoes each week, around 500,000 at a time at various sites yet to be identified. The mosquito factory, which is the largest in the world, is located in the city of Guangzhou, in southern China’s Guangdong, but the releases will be targeted in areas where disease poses the most threat. Only female mosquitoes bite, so scientists say there is no concern about adding to the problem since the bacteria infected mosquitoes they release will all be male.
The British biofirm Oxitec has been working on a similar project, aiming to release genetically modified male mosquitoes in Florida that would also disrupt the mosquito life cycle. After conducting tests in Panama, the Cayman Islands, and Brazil, scientists found an 80 percent reduction in wild mosquito populations. At the same time, MIT scientists are working to develop a ‘gene drive’ that would create a similar result. Genetically modified mosquitoes may be effective in reducing populations, but that approach doesn’t have the same generational effects as Wolbachia mosquitoes, because the genetic tweaks only impact one generation. No matter what method scientists use to make mosquito populations dwindle, logic follows that fewer disease-spreading mosquitoes will translate into a reduced risk of human infection. And who wouldn’t like to live in a world without mosquitoes?
Images via Michigan State University