A research team at the University of New Mexico has developed a technique to kill the Aedes aegypti, or yellow fever mosquito, which can spread the Zika, dengue and chikungunya viruses as well as other tropical diseases.
The researchers are using lemongrass oil to kill the mosquito larvae in water, researchers said.
Ravi Durvasula, an infectious disease researcher at the UNM School of Medicine’s Center for Global Health, said this technique of killing mosquitoes, developed by him and his team members, is cost-effective and works remarkably well.
He said the researchers are not targeting the diseases directly but rather their cause - mosquitoes.
Scott Matthews, who works in Durvasula’s lab at the UNM School of Medicine’s Center for Global Health, said the researchers tested the technique in the laboratory and achieved a 100 percent mortality rate.
He said the idea for the research came from hearing people speak at conferences and in person about the need for a way to kill mosquitoes in their larval state without poisoning the water supply.
“So, in most parts of the world, mosquitoes live near the water supplies that we use in our daily lives. The pesticides used to kill mosquitoes in water are to a lesser or greater degree toxic and poison water,” he said. “You may dump a lot of larvicides into water aiming to kill the mosquitoes, but you can end up killing other creatures, like frogs and fishes.”
He said the researchers wanted something that would be cheap, effective and non-toxic.
“The other motivation is that the poisons we use now, they attack different aspects of the physiology of these creatures and the problem with that is that if you just attack one or two specific features of an organism, it’s pretty easy for that organism to evolve resistance,” he said.
He said it only takes one larvae or mosquito to find a way to overcome that toxic mechanism and produce offspring for the pesticide to lose its efficacy.
“It is really a kind of losing proposition. This happened to DDT. Mosquitoes found resistance to DDT and researchers found about the resistance five years after the first mosquito developed that resistance,” he said.
He said he and his colleagues wanted to find an agent that would attack the larvae on many different fronts so the chance of the larvae evolving resistance to any one of them is really slim.
He said lemongrass oil has at least seven compounds in it found to have larvicidal effects.
“Each of them attacks (a) different aspect of larval physiology,” he said.
He said the nature of lemongrass oil and the compounds it contained have slim chances of being resisted by the larvae.
“The challenge was how to deliver that lemongrass to the larvae. Rain water or aiding water would dilute it. What we came up with was finding a delivery method to deliver it inside the stomach of those larvae,” he said.
He said the researchers decided to deliver the lemongrass to the stomach of the larvae through yeast, the food larvae love to eat.
“The yeast cell has (a) thick outer membrane. We found a way to get the (lemongrass) oil inside the yeast’s double membrane and kill the yeast but leave its outer membrane intact,” he said.
Matthews said the researchers packaged lemongrass oil inside the cells of yeast.
“The larvae think it is the usual yeast and consume it ... It is very much like the Trojan horse story. Specific targeting and deception have long been a way for insects to transmit disease. We thought of turning it around and use deception to kill the disease,” he said.
Sayyed Shah is assistant news editor at the Daily Lobo. He can be contacted at email@example.com or on Twitter @mianfawadshah.