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Toxic male mosquitoes will poison females with their semen in a new population control method developed by Australian researchers.
The method involves genetically engineering males to produce spider and sea anemone venom proteins, which they inject into females during mating, reducing their lifespan.
Macquarie University researchers have been testing the “toxic male technique” in a species of mosquito that spreads dengue fever, Zika and other viruses, after a study using fruit flies was published in peer-reviewed journal Nature Communications.
Lead author Sam Beach said the species-specific approach could be used to quickly suppress outbreaks of mosquito-borne diseases, such as dengue fever – which results in 390m cases world wide each year – without having to spray huge amounts of insecticides that can decimate local insects.
“Ideally, what we’re trying to achieve is: a male mosquito mates with a female and then she dies immediately,” he said.
Injecting a new gene into freshly laid mosquito eggs using tiny glass needles was “a very tedious process,” he added.
Only female mosquitoes are blood feeders. They generally mate within 24 to 48 hours of emerging, but can live and continue biting for several weeks, which enables the continued spread of disease.
The toxic male technique could reduce rates of blood feeding by 40-60%, according to the study.
While other genetic biocontrol approaches have used males to reduce the viability, blood-feeding or disease transmitting abilities of mosquito offspring, Beach said the new method targeted females directly.
“With this approach, we can immediately reduce the size of the female mosquito population and then hopefully get a really rapid reduction in the spread of these vector-borne illnesses.”
University of Melbourne evolutionary biologist, Dr Tom Schmidt, who was not involved in the study, said pesticide resistance was a global problem, prompting scientists to develop other pest management approaches.
“Mosquitoes get resistant to insecticides very rapidly, and they can spread resistance. They can evolve it, and they can also spread it by getting on boats and planes and spreading it all over the world.”
An Australian approach that infected mosquitoes with Wolbachia bacteria dramatically reduced dengue fever transmission in northern Queensland, he said. Genetic approaches could also work, he said, noting that mosquito control wasn’t a one-size-fits all approach.
Climate change was also causing species of mosquitoes to appear in places where they hadn’t been before.
Prof Philip Weinstein, an infectious diseases researcher at the University of Adelaide who was not involved in the study, said there were thousands of species of mosquitoes, but only a few carried diseases.
Weinstein said an ideal solution would be to control the insects without eradicating them, given that mosquitoes were pollinators and an important food source for fish and bats.
“Ecosystem health – things that happen in the environment, including mosquitoes but also water quality, air quality, climate change, biodiversity loss – all impact, either directly or indirectly, human health outcomes,” he said.
