Could the solution to the long battle against malaria be as simple as using soap? This intriguing possibility was presented in a recent study published in PLOS Neglected Tropical Diseases by scientists at the University of Texas at El Paso.
The team has discovered that adding small amounts of liquid soap to some kinds of pesticides can increase their potency more than tenfold.
The discovery is promising news, as malaria-carrying mosquitoes show increasing resistance to current insecticides, said Colince Kamdem, Ph.D., lead author of the study and assistant professor in the Department of Biological Sciences at UTEP.
“Over the last two decades, mosquitoes have become strongly resistant to most insecticides,” Kamdem said. “It is now a race to develop alternative compounds with new modes of action.”
Alternative insecticides and field trials
Both laboratory tests and field trials have shown that neonicotinoids, a special class of insecticide, are a promising alternative for target populations that show resistance to existing insecticides, said UTEP research assistant professor Caroline Fouet, Ph. .D., second author of the study. Neonicotinoids, however, do not kill some mosquitoes. species unless its power is increased. In this case, Fouet said, the soap is the stimulating substance.
Malaria is a devastating mosquito-borne disease prevalent in sub-Saharan Africa, Asia, and Latin America, causing fever, fatigue, headaches, and chills; the disease can be fatal. According to the Centers for Disease Control, there were an estimated 241 million cases of malaria worldwide in 2020, resulting in 627,000 deaths.
The power of soap discovered in Cameroon
Before joining UTEP, Kamdem worked at the Center for Research in Infectious Diseases (CRID) in Cameroon; It was there that he first realized the potency of soap while conducting routine insecticide testing.
Current World Health Organization (WHO) protocols for testing mosquito susceptibility to some insecticides recommend adding a seed oil-based product to insecticidal concoctions. Kamdem noted that when the compound was added, mosquito mortality increased compared to when the insecticide was used alone.
“That compound belongs to the same class of substances as kitchen soap,” Kamdem said. “We thought, ‘Why don’t we try products that have the same properties?’
He and his team selected three inexpensive linseed oil-based soaps prevalent in sub-Saharan Africa (Maître Savon de Marseille, Carolin Savon Noir, and La Perdrix Savon) and added them to four different neonicotinoids: acetamiprid and clothianidin. , imidacloprid and thiamethoxam.
The hunch paid off. In all cases, the insecticides dramatically improved potency, the team wrote in the study. “All three brands of soap increase mortality by 30 to 100 percent compared to when the insecticides are used alone,” said Ashu Fred, first author of the study and Ph.D. Student at the University of Yaoundé in Cameroon.
More research and potential applications
The team also tested adding soap to a class of insecticides known as pyrethroids. In those cases, however, they saw no benefit.
The team hopes to conduct additional tests to establish exactly how much soap is needed to improve insecticides.
“We would love to create a soap and insecticide formulation that can be used indoors in Africa and is healthy for users,” Kamdem said. “It is not known whether such a formulation will adhere to materials such as mosquito nets, but the challenge is promising and very exciting.”
Reference: “Plant oil-based surfactants are adjuvants that improve the efficacy of neonicotinoid insecticides and can bias susceptibility testing in adult mosquitoes” by Fred A. Ashu, Caroline Fouet, Marilene M. Ambadiang, Véronique Penlap-Beng and Colince Kamdem, November 17, 2023, PLOS Neglected Tropical Diseases.
Additional authors of the study are PhD student Marilene M. Ambadiang from CRID and the University of Yaoundé and Professor Veronique Penlap-Beng, Ph.D., from the University of Yaoundé.
The project was supported by a grant from National Institutes of Health.