Australia is leading two major assaults against the transmitting agent of mosquito-born menaces to humans in the tropics such as Dengue fever and others: the Aedes aegypti mosquito.
The perhaps more widely known project is the World Mosquito Program (WMP), which from a small project in northern Australia led by researchers from Monash University has developed into an international initiative operating in 12 countries.
The WMP explores the potential of so called Wolbachia bacteria as a control agent for viral diseases transmitted by A. aegypti mosquitoes.
Wolbachia is common in nature infecting many insect species, but does not usually occur in A. aegypti. However, A. aegypti mosquitoes that carry the bacteria have a reduced capacity to transmit viruses to people.
Researchers involved in the WMP have found a way to exploit this by rearing female and male insects infected with Wolbachia in the lab, and to release them in areas where the mosquito is causing outbreaks of viral diseases. The research found that Wolbachia then spreads in the mosquito populations without the need for further releases, as the bacteria are passed on with the insect's eggs.
While the focus of this method is not to reduce mosquito populations, it has been shown to protect communities from the viral diseases they transmit.
An alternative approach, however, aims to suppress mosquito numbers by releasing only male mosquitoes that carry Wolbachia. This is because non-infected female mosquitoes that mate with infected males are unable to reproduce, a natural phenomenon known as 'cytoplasmic incompatibility'.
The release of male insects that were sterilised, including through irradiation or Wolbachia infection, has been successfully used to reduce mosquito populations since the 1950s.
However, the challenge of using Wolbachia with A. aegypti mosquitoes has been to produce sufficiently large numbers of infected sterile males.
But a technology developed by Alphabet's life-science offshoot Verily now makes it possible to rear mosquitoes infected with Wolbachia in large quantities, and to then efficiently separate males from females.
The potential for suppressing A. aegypti populations was recently demonstrated in a trial, in which Verily collaborated with researchers from the CSIRO and James Cook University.
Between November 2017 and June 2018, the team released three million sterile A. aegypti male mosquitoes across the Cassowary Coast in Queensland, and found that this reduced mosquito populations by more than 80%.
"Verily's technology enabled us to do the sex sorting faster and with much higher accuracy," says Dr Kyran Staunton from James Cook University. "We learnt a lot from collaborating on this first tropical trial and we’re excited to see how this approach might be applied in other regions where A. aegypti poses a threat to life and health."