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‘Super’ mosquitoes have already mutated to withstand insecticides, scientists say

‘Super’ mosquitoes have already mutated to withstand insecticides, scientists say

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One of the most vicious types of pests on the planet continues to outsmart the ways people try to get rid of them.

“Super” mosquitoes have evolved to withstand insecticides, according to new research – and the most “sobering” finding is the high rate at which a species known to carry disease has developed mutations.

Researchers at the National Institute of Infectious Diseases in Japan have studied mosquitoes in dengue-endemic areas in Vietnam and Cambodia and found that they harbor mutations that endow them with strong resistance to common insecticides, according to a study published in Scientific progress on Wednesday.

One of the most worrisome mutations appeared in about 78 percent of collected specimens of Aedes aegypti — one of the most notorious mosquito species and a major vector of dengue, yellow fever and the Zika virus, according to the study.

A municipal worker sprays anti-mosquito chemicals during a fumigation operation against the Aedes Aegypti and Aedes Albopictus mosquitoes responsible for transmitting dengue, Zika and chikungunya, April 27, 2022 in San Salvador, El Salvador.

Aphotografia/Getty Images, FILE

The development of resistant pyrethroids often occurs when mutations occur in the Vgsc gene, which encodes the molecular target of pyrethroids, the paper states. The researchers discovered 10 new sub-strains of Ae. aegypti and noticed that one Vgsc mutation — called L982W — gave mosquitoes high resistance to the pyrethroid insecticide permethrin in the lab.

This mutation occurred at a frequency of more than 79% in mosquitoes collected from Vietnam, and mosquitoes in Cambodia harbored combinations of L982W and other Vgsc mutations that showed “extreme” levels of pyrethroid resistance, the researchers said.

The L982W mutation has not been found outside of Vietnam and Cambodia, but researchers believe it may be slowly spreading to other parts of Asia.

The findings could pose a serious threat to infectious disease control and eradication programs because the mutation is one of the highest levels of insecticide resistance seen in a field population of mosquitoes, the researchers said.

PHOTO: FILE - Male culicides, vector of tropical diseases, mosquito, commonly called

Male Culicidae tropical disease vector mosquitoes, commonly called “mosquito da dengue” in Brazil, are the vector for chikungunya, yellow fever, and dengue.

Joao Paulo Burini/Getty Images, FILE

Many health initiatives rely on pyrethroids and other insecticides to control mosquito-borne infections, especially those for which there is no vaccine, such as dengue.

“It’s important to be aware that the insecticides we normally use may not be effective against mosquitoes,” Shinji Kasai, study author and senior research fellow in NIID’s Division of Medical Entomology, told ABC News.

It will be necessary to continue to monitor these mutant alleles, especially in Southeast Asia, to take appropriate countermeasures before they spread globally, Kasai said. In addition, alternating between different insecticide groups is sometimes effective, Kasai added.

“Government health officials should select an appropriate, more effective insecticide for mosquito control,” he said.

Mosquitoes appear to have evolved both physically and instinctively to avoid human attempts to eradicate their presence.

In February, scientists published a study that mosquitoes learn to avoid pesticides used to kill them.

Scientists who studied two species of mosquitoes – Aedes aegypti and Culex quinquefasciatus – found that females learned to avoid pesticides after a single non-lethal exposure.


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