Study discovers mutation responsible for mosquito insecticide resistance

Researchers from the Liverpool School of Tropical Medicine recently discovered a genetic mutation responsible for mosquito resistance to DDT and pyrethroid insecticides commonly used in mosquito nets.

The study, which was led by Dr. Charles Wondji, sought to discover why some mosquitoes are developing resistance to common insecticides, an emerging challenge to malaria control methods. The team found that most mosquitoes resistant to DDT are also resistant to pyrethroids, so researchers analyzed the genetic make-up of both resistant and susceptible mosquitoes most responsible for malaria and discovered a genetic mutation.

"We found a population of mosquitoes fully resistant to DDT but also to pyrethroids," Wondji said. "So we wanted to elucidate the molecular basis of that resistance in the population and design a field applicable diagnostic assay for its monitoring.'

The researchers found that a single genetic mutation, L119F, changed the GSTe2 gene to develop resistance to DDT and pyrethroids. The researchers also discovered that the only areas in the world with mosquitoes resistant to DDT and pyrethroids are the same areas that have mosquitoes that express this genetic mutation.

"For the first time, we have been able to identify a molecular marker for metabolic resistance in a mosquito population and to design a DNA-based diagnostic assay," Wondji said. "Such tools will allow control programs to detect and track resistance at an early stage in the field, which is an essential requirement to successfully tackle the growing problem of insecticide resistance in vector control. This significant progress opens the door for us to do this with other forms of resistance as well and in other vector species."