How Soap Help Combat Malaria-Spreading Mosquitos?

Mixing modest amounts of liquid soap with certain classes of pesticides can increase their efficacy by more than ten-fold. The finding is promising as mosquitoes that transmit malaria are becoming more resistant to the current pesticides. The study was led by scientists at The University of Texas at El Paso (UTEP) and published in PLOS Neglected Tropical Diseases (1^✔ ✔Trusted Source
Vegetable oil-based surfactants are adjuvants that enhance the efficacy of neonicotinoid insecticides and can bias susceptibility testing in adult mosquitoes

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Pesticides with Soap Battle Malaria-Carrying Mosquitos

“Over the past two decades, mosquitoes have become strongly resistant to most insecticides,” Kamdem said. “It’s a race now to develop alternative compounds with new modes of action.”

Both laboratory tests and field trials have shown that neonicotinoids, a special class of insecticide, are a promising alternative to target populations showing resistance to existing insecticides, said Caroline Fouet, Research Assistant Professor at UTEP.

Neonicotinoids, however, do not kill some mosquito species unless their potency is boosted. In this case, Fouet said, soap is the boosting substance. Malaria is a devastating mosquito-borne disease that is prevalent in sub-Saharan Africa, Asia, and Latin America, causing fever, fatigue, headaches, and chills; the disease can be fatal.

In 2020, there were an estimated 241 million cases of malaria worldwide, according to the Centers for Disease Control, resulting in 627,000 deaths. In a new study, the team selected three low-cost, linseed-oil based soaps that are prevalent in sub-Saharan Africa -- Maitre Savon de Marseille, Carolin Savon Noir, and La Perdrix Savon -- and added them to four different neonicotinoids, acetamiprid, clothianidin, imidacloprid, and thiamethoxam.

In all cases, the insecticides drastically enhanced potency, the team wrote in the study .“All three brands of soap increase mortality from 30 percent to 100 percent compared to when the insecticides were used on their own,” said Ashu Fred, first author and doctoral student at Cameroon’s University of Yaounde.

The team also tested the addition of soap to a class of insecticides known as pyrethroids. In those cases, however, they saw no benefits. The team hopes to conduct additional testing to establish exactly how much soap is needed to enhance insecticides.

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“We would love to make a soap-insecticide formulation that can be used indoors in Africa and be healthy for users,” Kamdem said. “There are unknowns as to whether such a formulation will stick to materials like mosquito nets, but the challenge is both promising and very exciting.”

Reference:

1. Vegetable oil-based surfactants are adjuvants that enhance the efficacy of neonicotinoid insecticides and can bias susceptibility testing in adult mosquitoes - (https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0011737)

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