Monitoring Desk
ISLAMABAD: A new research has warned that mosquitoes that transmit dengue and other viruses have evolved growing resistance to pesticides in parts of Asia, and novel ways to control them were desperately needed.
Resistance to pesticides has long been a problem, and health authorities frequently fog mosquito-infested areas with chemical clouds, but the scope of the issue was not understood.
Shinji Kasai, a Japanese scientist, and his team examined mosquitos from several countries in Asia and Ghana. They discovered that specific individuals were almost immune to typical pyrethroid-based insecticides like permethrin due to mutations.
High level of resistance in Aedes aegypti mosquitoes
The combination of mutations that leads to an extraordinarily high level of resistance is present in more than 90% of Aedes aegypti mosquitoes in Cambodia, according to Kasai, who spoke to AFP. He discovered that some mosquito strains were 1,000 times more resistant.
That meant insecticide levels that would typically kill almost 100 percent of mosquitoes in a sample killed only around seven percent of the insects.
Around 30 percent of the super-resistant mosquitoes were killed in a dose more potent, even ten times.
“We found the resistance level in Vietnam, and Cambodia is different,” said Kasai, director of the Department of Medical Entomology at Japan’s National Institute of Infectious Diseases.
According to the World Health Organization, dengue can cause hemorrhagic fever and affects between 100 and 400 million people annually, but over 80% of cases are mild or asymptomatic.
Researchers have created several dengue vaccinations and utilized a microbe that kills mosquitoes to combat the illness. However, neither approach has come near eliminating dengue because Aedes aegypti mosquitoes also spread yellow fever and zika.
New formulas required-
Resistance was also detected in Aedes albopictus, another type of mosquito, but at a low level, perhaps due to its feeding outdoors on animals; therefore, it is more exposed to insecticides than Aedes aegypti, human-loving counterparts.
The study discovered many gene mutations, including two near the region of mosquitoes targeted by pyrethroid and several other insecticides, were associated with resistance.
The resistance levels varied, with Ghanaian mosquitoes and some Indonesian and Taiwanese mosquitoes still being quite sensitive to current insecticides, especially at higher dosages.
But according to Cameron Webb, an associate professor and mosquito researcher at NSW Health Pathology and the University of Sydney, the data indicates that “frequently used techniques may no longer be successful.”
According to Webb, there is “increasing evidence that present insecticide formulations may not be effective in reducing populations of important mosquito pests.” He stated that while new chemicals are required, authorities and researchers must also consider other community protection measures, like immunizations.
Kasai, whose study was published in Science Advances last month, said, “We have to consider rotating pesticides… that have different targeted areas.” The issue is that we need to be more expansive in the types of materials we may utilize.
Kasai is expanding the research outside of Asia and looking at more recent samples from Vietnam and Cambodia to determine whether anything has changed from the 2016–2019 study period. When and where the mutations for resistance originated is still a mystery.
The mosquitoes with the mutations we discovered in this study, he continued, “will likely spread to the rest of the planet soon.” “But first, we need to come up with a solution.”
