Most Dengue Insecticides No Longer Work, Study Reveals
A new study shows that common insecticides used against Aedes mosquitoes in Bangladesh are failing. These mosquitoes carry the dengue virus. They have developed strong resistance to many chemicals. This situation creates a serious public health challenge.
Researchers tested six different insecticides in Dhaka and Chattogram. They found that five of these chemicals could not effectively kill the Aedes mosquitoes. This important research was led by Professor Kabirul Bashar. He is from the Department of Zoology at Jahangirnagar University. Experts from Japan’s Institute of Health Security also joined the study.
The team found alarming results. For some insecticides, even a tenfold increase in concentration did not kill the mosquitoes. For example, 90 percent of Aedes mosquitoes in Dhaka survived a strong dose of permethrin. In Chattogram, 84 percent survived the same chemical. Similar resistance was seen with etofenprox and deltamethrin.
The study identified only one effective chemical: malathion. This organophosphate insecticide killed 98 percent of mosquitoes within 24 hours. This result was consistent for mosquitoes collected from both Dhaka and Chattogram. However, scientists warn against relying solely on malathion. Continuous use could lead to resistance against it as well.
Professor Bashar’s team also found two genetic changes in the mosquitoes. These mutations help them resist insecticides. Touhid Uddin Ahmed, a former chief scientific officer at IEDCR, commented on the findings. He said the resistance development has serious dangers. He explained that new insecticides might also become ineffective quickly. This problem is known as “cross-resistance.”
The study focused on insecticides from three main groups. These were pyrethroids, carbamates, and organophosphates. Aedes aegypti mosquitoes showed resistance to all four pyrethroid insecticides tested. They also resisted bendiocarb, a carbamate chemical. Only malathion, from the organophosphate group, remained effective.
Public health expert Mushtuq Husain stressed the need for new approaches. He said using only chemical sprays will no longer be enough. He suggested adding biological methods to control mosquitoes. Mr. Husain also emphasized the importance of regular monitoring. He said we need to track mosquitoes, dengue patients, and insecticide effectiveness. This information is currently missing but is vital for preventing dengue. The research began in 2023 and is still ongoing.
