You might say cottagers maintain a love-hate relationship with the myriad insects that tend to cohabitate our lakeside retreats. But when it comes to mosquitoes, there’s no love lost between humans and these bloodthirsty critters.
While cottagers may wage their own annual wars against mosquitoes in hopes of foregoing the mildly annoying itch of their bites, across the world, the threat of mosquito-born diseases, such as malaria and dengue fever, are creating much higher stakes.
In hopes of reducing mosquito populations in regions where mosquitos carry these fatal diseases, researchers at the University of Maryland have engineered a floral-scented fungi that lures and kills the deadly insect—an advancement in biotechnology that has the potential to save both lives and s’more roasting sessions.
“In Africa, for example, mosquitoes are infecting a couple hundred million people a year with malaria, and half a million, mostly children, die of it,” says Raymond St. Leger, one of the co-authors of the study. In more recent times, he adds, outbreaks of malaria and dengue have occurred in places they never have before, such as Europe and North America, further heightening the need for efficient mosquito control.
In the past, chemical insecticides were the go-to solution, but St. Leger says this approach isn’t as effective as it once was. “The mosquitoes which carry these diseases are insecticide-resistant, so we’re looking for alternatives.”
Enter the mosquito-killing fungi.
The fungi, known scientifically as Metarhizium fungi, was discovered by the study’s other co-author, Etienne Bilgo, who came across a dead mosquito in a small hut in Burkina Faso that had been killed by a naturally-occurring fungus. It was found that a mosquito killed by this specific type of fungus would emit a sweet-smelling floral scent, but only from the body of the dead insect.
Back in Maryland, St. Leger and Bilgo set off bio-engineering the fungi to produce the floral scent on its own, which would then attract mosquitos to the deadly fungus. Able to grow on any nutrient medium, the fungi can be placed inside of a trap to attract, catch, and kill hungry mosquitoes.
During trials, the fungus proved to be extremely effective. “[The study] was very successful,” says St. Leger. “We tested it in a very large room. We had kids sleeping under bug netting, and we released the mosquitoes with some of the floral-odour fungus at the far end of the room, and the mosquitoes made their way to the fungus, got into it, and died.”
But while the fungi traps work well to eliminate mosquitos in small areas, St. Leger says more field trials are needed to assess how effective the technology can be at quelling mosquito-born diseases on a large scale.
“We know we can kill the mosquitoes, but what’s the real question we’re interested in?” says St. Leger. “The real question is, can we kill enough mosquitoes to reduce disease? How many mosquitoes do you have to kill to achieve that?”
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