[NAIROBI] A genetic biocontrol method that reduces the lifespan of female insects could work as quickly as pesticides to reduce populations of disease-carrying mosquitoes and destructive crop pests, researchers say.
Insect pests pose a huge threat to global health and agriculture, causing hundreds of thousands of deaths, millions of infections, and costing billions in healthcare and crop damage each year.
Biological control is increasingly seen as a viable alternative to pesticides, which can harm non-target species and ecosystems and lose effectiveness as resistance increases.
“In a few years, we are confident that our technology will provide millions of people around the world with a sustainable solution to combat crop diseases and pests.”
Samuel Beach, Macquarie University, Australia
A new approach called Toxic Male Technique (TMT), developed by researchers at the ARC Center of Excellence in Synthetic Biology at Macquarie University, Australia, involves genetically modifying male insects to reduce the lifespan of the females they mate with.
Researchers say it can be used to quickly respond to agricultural pest outbreaks as well as to combat mosquito-borne diseases such as malaria, dengue and Zika.
“We believe our technology has the potential to act as quickly as pesticides without the associated risks of harming other species and the environment,” says Samuel Beach, an applied bioscience researcher at Macquarie University and lead author of the study, published on January 7 in Nature Communications.
According to the latter, this approach is more effective than existing methods such as the sterile insect technique or the release of insects carrying lethal genes, which involves releasing masses of sterilized or genetically modified males to mate with wild females.
By this technique, females do not produce offspring, if so only male offspring, but they continue to feed on blood and spread diseases until they die naturally. Which means that populations of biting females only decrease over generations.
“TMT is less expensive because few males are needed to achieve a much faster reduction in the insect population or to have a reduction in the spread of diseases,” explains Samuel Beach.
Venom
The new technique involves genetically modifying male insects to produce specific venom proteins in their sperm. When these males mate with females, proteins are transferred, significantly reducing the females’ lifespan and ability to spread disease.
Researchers found that mating females with genetically modified males reduced their lifespans by 60%.
“Ideally, we are looking at a 100% reduction in lifespan, that is, the females die as soon as they mate with the male,” the researcher tells SciDev.Net. “But this is what we want to achieve in the long term, it will take time,” he adds.
Even a 60% reduction could go a long way toward reducing the impact of mosquito-borne diseases, he says.
-Diseases such as malaria, dengue, Zika virus, chikungunya and yellow fever are transmitted by female mosquitoes of the Aedes species aegypti and Anopheles gambiae.
Samuel Beach explains that when the female mosquito feeds on the blood of a host and contracts the microbe, she is not contagious for a few days. For a period of five to ten days, she cannot transmit the disease to another person.
“This means we don’t need to achieve 100% mortality; we just need to reduce her lifespan during that period where she can’t pass this disease on to a second person, which we estimate is a reduction in lifespan of about 60-80%,” he explains.
According to the study authors, this technology could work even better for farmers because crop pests have a longer lifespan than mosquitoes, up to a year or two, compared to three to four weeks.
“Since the generation time is very long, if we can kill the female earlier, it will have a much greater benefit for agricultural pests,” adds Samuel Beach.
Operational costs
Tonny Owalla, laboratory researcher Med Biotech of Kampala, Uganda, who was not involved in the study, believes that modifying male mosquitoes to reduce the population of malaria-carrying females could be a useful approach.
He fears, however, that the costs of deploying this technology will make it impractical for routine use in countries where malaria is endemic.
“For example, how many male mosquitoes should we deploy in the Democratic Republic of Congo, which is the first malaria endemic country in Africa, how many releases will be necessary per year, what infrastructure will be necessary, what would be the source of supply of mosquitoes…? », Asks Tony Owalla.
Samuel Beach says the technology must undergo rigorous safety testing before adoption, while regulatory frameworks to guide its use and infrastructure for breeding mosquitoes will also be needed.
“However, in a few years, we are confident that our technology will provide millions of people around the world with a sustainable solution to combat crop diseases and pests,” he says.
The original version of this article was produced by the English edition of SciDev.Net for Sub-Saharan Africa.
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