A CSIRO-led research team has recorded a landmark victory in the battle against Aedes aegypti, the mosquito species that transmits a number of deadly diseases worldwide.
Researchers have achieved a breakthrough in controlling the notorious invasive mosquito Aedes aegypti. The landmark trial has shown that the Wolbachia bacterium can successfully sterilise and eradicate populations of the mosquitoes, with a success rate of 80-97%. Found on every continent except Antarctica, Aedes aegypti is responsible for spreading diseases such as dengue, yellow fever and Zika. The breakthrough puts researchers on a path of suppression and potentially eradication of Aedes aegypti worldwide.
The trial was an international collaboration between CSIRO, University of Queensland, Verily Life Sciences, QIMR Berghofer Medical Research Institute and James Cook University, which saw contemporary science working together with cutting-edge technology. Published in PNAS, the trial involved releasing three million male Aedes aegypti mosquitoes in Northern Queensland, sterilised with the Wolbachia bacteria. They were released across three trial sites over a 20-week period during the summer of 2018. The aim was for sterile male insects to search out and mate with wild females, producing eggs that were unviable, preventing the production of offspring.
Returning after 12 months, the trial was found to be hugely successful, with the majority of the mosquitoes eliminated. “During the trial, we saw over 80% of the mosquito population suppressed across our three trial sites,” said CSIRO scientist and UQ Associate Professor, Nigel Beebe. “When we surveyed the sites the following year, we were very encouraged to see the suppression still in effect, with one of our most productive towns for Aedes aegypti almost devoid of this mosquito with a 97% reduction across the following season. “One year on, the mosquito population at the second trial site remained substantially suppressed, while the population had fully recovered at the third site.
“We are currently investigating the differences observed in the following mosquito season as they are incredibly informative in further developing this technology and in modelling how we could remove this exotic virus transmitting pest in other locations worldwide.” To produce the three million male mosquitoes needed for the trial, researchers at James Cook University 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,” said Dr Kyran Staunton from James Cook University.
To address this challenge, Verily, an affiliate of Alphabet Inc (Google parent company), developed a mosquito rearing, sex sorting and release technology as part of its global Debug project. “Verily’s technology enabled us to do the sex sorting faster and with much higher accuracy,” Dr Staunton added. Verily product manager Nigel Snoad commented, “It was a huge achievement by the joint team to set up and operate the mosquito rearing, sorting and release systems, and develop strong community engagement and support.”
CSIRO director of Health and Biosecurity Dr Rob Grenfell said the results were a major win in the fight against disease-spreading mosquitoes. “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% of infectious disease transmissions globally,” he 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.” Techniques from the trial are being used to support other CSIRO-led mosquito suppression programs and there is discussion of using the technique to control the virus transmitting Asian tiger mosquito, Aedes albopictus, which has established in the Torres Strait Islands.
Source: CSIRO media releases. ‘Trial wipes out more than 80 per cent of disease-spreading mozzie’ and ‘Landmark trial eliminates pest mosquito’ by Asaesja Young. October 5, 2021.