CSIRO

In an international partnership between CSIRO, Verily and James Cook University, scientists used specialised technology to release millions of sterilised male Aedes aegypti mosquitoes across the Cassowary Coast in Queensland in a bid to combat the global pest.

CSIRO Director of Health and Biosecurity Dr Rob Grenfell said the results were a major win in the fight against diseases-spreading mosquitoes.

“The invasive Aedes aegypti mosquito is one of the world’s most dangerous pests, capable of spreading devastating diseases like dengue, Zika and chikungunya and responsible for infecting millions of people with disease around the world each year,” Dr Grenfell said.

“Increased urbanisation and warming temperatures mean that more people are at risk, as these mosquitoes which were once relegated to areas near the equator forge past previous climatic boundaries.

“Although the majority of mosquitoes don’t spread diseases, the three mostly deadly types the Aedes, Anopheles and Culex are found almost all over the world and are responsible for around 17 per cent of infectious disease transmissions globally.”

From November 2017 to June this year, non-biting male Aedes aegypti mosquitoes sterilised with the natural bacteria Wolbachia were released in trial zones along the Cassowary Coast in North Queensland.

They mated with local female mosquitoes, resulting in eggs that did not hatch and a significant reduction of their population.

“Our heartfelt thanks goes out to the Innisfail community who literally opened their doors to our team, letting us install mosquito traps around their homes and businesses – we couldn’t have done this without your support,” Dr Grenfell said.

The process, known as the Sterile Insect Technique, has been successfully used since the 1950s but the challenge in making it work for mosquitoes like the Aedes aegypti has been rearing enough mosquitoes, removing biting females, identifying the males and then releasing the huge numbers needed to suppress a population.

To address this challenge, Verily, an affiliate of Alphabet Inc, developed a mosquito rearing and sex sorting and release technology as part of its global Debug project.

“We’re very pleased to see strong suppression of these dangerous biting female Aedes aegypti mosquitoes,” Verily’s Nigel Snoad said.

“We are particularly thankful to the people of Innisfail for their strong support, which has been incredible.

“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.”

Scientists compared the number of Aedes aegypti mosquitoes trapped in release sites and control zones to monitor and track populations.

The millions of mosquitoes needed for the trial were reared at James Cook University in Cairns.

To produce the three million male mosquitoes needed for the trial, researchers at James Cook University (JCU) in Cairns set out to raise almost 20 million Aedes aegypti.

“We allowed for the possibility of deaths during the process, as well as the need to sift out the female half of the population,” Dr Kyran Staunton from James Cook University said.

“Verily’s technology enabled us to do the sex sorting faster and with much higher accuracy.

“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 Aedes aegypti poses a threat to life and health.”

“The health of our nation is paramount as we help Australia achieve its vision to become one of the healthiest nations on earth,” CSIRO Chief Executive Dr Larry Marshall said.

“By enabling industry partners like Verily to leverage the world-leading health capability we have built in CSIRO we can deliver this moonshot and tackle some of the world’s most wicked challenges with science.”