Australia may be the home of koalas, Tim Tams, and hipster coffee joints selling broccoli lattes, but the one thing it is really known for is its abundance of animals out to kill you. The humble mozzie might not draw as much attention as the huntsman spider but it can be far deadlier. Take the Aedes aegypti, also known as the yellow fever mosquito, as an example. The bloodsucking parasite has a well-earned reputation for spreading tropical diseases like Zika and dengue fever.
Now, thanks to an international partnership between Commonwealth Scientific and Industrial Research Organization (CSIRO), Verily, and James Cook University, scientists have been able to eradicate more than 80 percent of these disease-carrying mozzies in three trial locations.
In what sounds like a self-defeating move, the team bred 20 million mosquitoes in a lab and proceeded to release 3 million in three towns on the Cassowary Coast last summer. Of course, these weren't your standard mozzies. These were male mosquitoes genetically engineered to be infertile. And because males don't bite (they prefer to chomp on plant nectar), there was no risk they would spread disease. Instead, they spent their time mating with females who went on to lay eggs that never hatched.
As a result, the population crashed. In just eight months (November 2017 to June 2018), the Aedes aegypti dropped 80 percent in the trial locations, which is good news for the residents of north Queensland.
"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," Rob Grenfell, CSIRO director of health and biosecurity, said in a statement.
"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 percent of infectious disease transmissions globally."
Once confined to areas near the equator, the distribution of the Aedes aegypti is spreading thanks to a combination of urbanization, human movement, and climate change. The eradication of this bug should not cause too much ecological damage to Australia because it is not a native species.
This isn't the first time scientists have harnessed the power of male infertility to take on unwanted pests. It's a method called the Sterile Insect Technique and it has been around since the fifties. While laboratory-based studies have applied this practice to disease-carrying mosquitoes, implementation is tricky because of the large numbers of infertile males needed, difficulties in separating the sex of the mosquitoes, and the practicality of releasing them in numbers high enough to suppress a population. Fortunately, new technology is making this easier.
Trials have been restricted to north Queensland for the time being, though Verily has announced it may organize additional tests. Meanwhile, similar trials are currently taking place in Brazil and the Cayman Islands.
To learn more about the process, watch the video here:
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