S China lab sterilizes mosquitos to fight dengue, Zika

A lab in China is aiming to sterilize mosquitos to cut off transmission of dengue and Zika virus after pesticides and medication have proved to have limited effects.

The lab at Sun Yat-sen University in Guangzhou, capital of south China's Guangdong Province, is rearing male mosquitos with a naturally occurring bacterium, called wolbachia, that sterilizes females to reduce the mosquito population and transmission of mosquito-borne diseases.

The largest of its kind, the lab covers an area of over 3,500 square meters and is divided into four sections, each capable of raising 5 million wolbachia-carrying male mosquitos.

The mosquitos hatch in cages designed to allow only males, which are usually a bit smaller, to filter through and be released.

Researchers at the lab said the filtering process is currently done manually, but they are working toward a more efficient automated filtering process.

These grown male mosquitoes are then released at a ratio of five sterile males to each non-sterile male in the wild, giving females an 80-percent chance of mating with them and becoming sterilized.

"Since female mosquitos only mate once in their lives, we want them to mate with our (wolbachia-carrying) males so the larvae they produce will not hatch," said Xi Zhiyong, who leads the lab's research on the Sterile Insect Technique project.

Last year, around 6.5 million male mosquitos were released at experiment sites, resulting in a nearly 100-percent elimination rate of mosquito larvae.

The research team hopes to see the technique gain widespread use in two to three years as an alternative to pesticides, which also hurt beneficial insects such as butterflies and bees and have decreased in effectiveness as mosquitos begin to develop antibodies. Endi