Some mosquitoes spread diseases to humans through their bite, passing along harmful pathogens like Zika, dengue fever, West Nile virus and chikungunya. Now humans are turning the tables, infecting these dangerous mosquitoes with bacteria that sabotage their ability to spawn.

Chinese researchers were able to reduce these mosquito populations by as much as 94% using a bacteria-based strategy that interferes with the insects' reproductive cycle.

"In principle, all the mosquito-borne diseases, including dengue, malaria, West Nile, chikungunya and filariasis, can be controlled using this technology," said senior study author Zhiyong Xi. He is director of the Sun Yat-sen University/Michigan State University Joint Center of Vector Control for Tropical Diseases. "There will be none of those diseases without transmission by mosquitoes."

The mosquito control strategy hinges on bacteria called Wolbachia, which can affect the reproductive biology of mosquitoes, said Peter Armbruster, a professor of biology at Georgetown University, in Washington, D.C.

Essentially, a male mosquito carrying a specific strain of Wolbachia cannot successfully reproduce if the female is infected with a different strain of Wolbachia, explained Armbruster, who wrote an editorial accompanying the report in the July 17 issue of the journal Nature.

The Chinese research team created a lab-based colony of mosquitoes that all carry a newly developed combination of three Wolbachia strains. This hybrid strain doesn't occur in the wild. The colony produced around 10 million male mosquitoes a week, Xi said.

The male mosquitoes were then released into the wild, in areas designated for pest control.

"They mate with wild females and then the wild females produce inviable eggs," Armbruster said. "It's a way of letting the males do the work by finding the females and preventing them from reproducing."

The researchers also treated the mosquitoes with a low dose of radiation, enough to sterilize any accidentally released females carrying the triple bacteria strain but not enough to impair the male mosquitoes' reproductive drive. This helped speed up laboratory production of the mosquitoes, Armbruster explained.

Field trials focused on Aedes albopictus mosquitoes were able to drive populations down by around 83% to 94%, with no wild mosquitoes detected for up to six weeks after release, the researchers reported.

Dr. Amesh Adalja is senior scholar at the Johns Hopkins Center for Health Security in Baltimore. "Mosquitoes have long been a scourge of mankind and their effective control is one of the most daunting tasks in infectious diseases," he said.

"Exploiting the phenomenon of mating incompatibility through male mosquito Wolbachia infections, combined with irradiation, is an elegant solution that this study demonstrates is feasible," Adalja said.

At least one American company, MosquitoMate, is already using a similar bacteria-based approach to control mosquitoes, Armbruster noted. The innovation in the study was the combination of three different Wolbachia strains and the use of radiation to make sorting and releasing mosquitoes an easier process.

You don't want to release both male and female mosquitoes with the triple strain, because they'll be able to successfully mate. Until now, lab technicians have had to run the mosquito swarms through a machine that separated males from females, and then do a second hand-sort to make sure all the females had been removed, Armbruster said.

 HealthDay