An impressive Australian trial that released millions of sterilized male mosquitoes in Queensland has resulted in a more than 80 percent drop in the population of this disease-spreading insect. The international collaboration involved scientists from Australia's James Cook University (JCU) and the CSIRO, working with a new mosquito-rearing technology developed by Verily, an independent subsidiary of Google's parent company Alphabet.

Between November 2017 and June this year millions of male Aedes aegypti mosquitoes infected with a naturally occurring bacterium called Wolbachia were released across several trial zones across the Cassowary Coast in Northern Queensland. The infected mosquitoes still mate naturally with females but the subsequent eggs do not hatch, allowing for rapid and significant drops in the local mosquito population.

The technique has been broadly utilized for over half a century, and has been proven to be a safe and effective way to manage insect populations, but deploying it on a larger scale has always been a challenge. The big technological innovation comes from Verily's automated mass-rearing system that efficiently and robotically rears large volumes of mosquitoes and separates the sexes. It's vital that only male mosquitoes are released into neighborhoods as males are non-biting, so when they are let loose in their millions they don't have a noticeable impact on human populations.

Verily is currently working to pilot its technology in a number of locations around the world, most prominent is its Debug Fresno project that began in 2017 with the release of nearly 20 million male mosquitoes across two neighborhoods in Fresno County, California. The initial results of the Debug Fresno project saw a 68 percent reduction in biting, female Aedes aegypti mosquitoes compared to other neighborhoods.

This Australian trial of the technique has shown similar, if not slightly better, results in a previously untested tropical environment.

"We came to Innisfail with CSIRO and JCU to see how this approach worked in a tropical environment where these mosquitoes thrive, and to learn what it was like to operate our technology with research collaborators as we work together to find new ways to tackle these dangerous mosquitoes," explains Nigel Snoad from Verily.

Another Australian project, called the World Mosquito Program, has been operating since 2011 using a similar Wolbachia infection technique. That project releases smaller volumes of both male and female Wolbachia-infected mosquitoes into the environment with the goal of slowly reducing the ability for female mosquitoes to transmit viruses. The Verily Debug project, on the other hand, is more geared towards rapidly suppressing local mosquito populations in shorter periods of time.

Source: CSIRO

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