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Credit: Morgana Wingard
A single genetic mutation can cause resistance to the main insecticides used to combat malaria, according to a study published in Genome Biology.
Researchers identified a mutation in the gene GSTe2 that allows mosquitoes to break down the insecticide DDT into non-toxic substances.
The mutation also makes mosquitoes resistant to pyrethroids, an insecticide class used in mosquito nets.
“We found a population of mosquitoes fully resistant to DDT but also to pyrethroids,” said study author Charles Wondji, PhD, of the Liverpool School of Tropical Medicine in the UK.
“So we wanted to elucidate the molecular basis of that resistance in the population and design a field-applicable diagnostic assay for its monitoring.”
To that end, the researchers did a genome-wide comparison on mosquitoes that were fully susceptible to insecticides and Anopheles funestus mosquitoes from the Republic of Benin in Africa, which were resistant to DDT and the pyrethroid permethrin.
The team found the GSTe2 gene was upregulated in the resistant mosquitoes. And a single mutation (L119F) changed a non-resistant version of the gene to an insecticide-resistant version.
The researchers then designed a DNA-based diagnostic test for this metabolic resistance and confirmed that this mutation was found in mosquitoes from other areas of the world with DDT resistance, but it was completely absent in regions without resistance.
X-ray crystallography of the protein coded by the gene illustrated exactly how the mutation conferred resistance—by opening up the active site where DDT molecules bind to the protein so that more can be broken down. In other words, the mosquito can survive by breaking down the poison into non-toxic substances.
The researchers also introduced the gene into Drosophila melanogaster and found the flies became resistant to DDT and pyrethroids, whereas control flies did not. The team said this confirms that a single mutation is enough to make insects resistant to both DDT and pyrethroids.
“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,” Dr 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.” 
spray insecticide
Credit: Morgana Wingard
A single genetic mutation can cause resistance to the main insecticides used to combat malaria, according to a study published in Genome Biology.
Researchers identified a mutation in the gene GSTe2 that allows mosquitoes to break down the insecticide DDT into non-toxic substances.
The mutation also makes mosquitoes resistant to pyrethroids, an insecticide class used in mosquito nets.
“We found a population of mosquitoes fully resistant to DDT but also to pyrethroids,” said study author Charles Wondji, PhD, of the Liverpool School of Tropical Medicine in the UK.
“So we wanted to elucidate the molecular basis of that resistance in the population and design a field-applicable diagnostic assay for its monitoring.”
To that end, the researchers did a genome-wide comparison on mosquitoes that were fully susceptible to insecticides and Anopheles funestus mosquitoes from the Republic of Benin in Africa, which were resistant to DDT and the pyrethroid permethrin.
The team found the GSTe2 gene was upregulated in the resistant mosquitoes. And a single mutation (L119F) changed a non-resistant version of the gene to an insecticide-resistant version.
The researchers then designed a DNA-based diagnostic test for this metabolic resistance and confirmed that this mutation was found in mosquitoes from other areas of the world with DDT resistance, but it was completely absent in regions without resistance.
X-ray crystallography of the protein coded by the gene illustrated exactly how the mutation conferred resistance—by opening up the active site where DDT molecules bind to the protein so that more can be broken down. In other words, the mosquito can survive by breaking down the poison into non-toxic substances.
The researchers also introduced the gene into Drosophila melanogaster and found the flies became resistant to DDT and pyrethroids, whereas control flies did not. The team said this confirms that a single mutation is enough to make insects resistant to both DDT and pyrethroids.
“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,” Dr 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.”
spray insecticide
Credit: Morgana Wingard
A single genetic mutation can cause resistance to the main insecticides used to combat malaria, according to a study published in Genome Biology.
Researchers identified a mutation in the gene GSTe2 that allows mosquitoes to break down the insecticide DDT into non-toxic substances.
The mutation also makes mosquitoes resistant to pyrethroids, an insecticide class used in mosquito nets.
“We found a population of mosquitoes fully resistant to DDT but also to pyrethroids,” said study author Charles Wondji, PhD, of the Liverpool School of Tropical Medicine in the UK.
“So we wanted to elucidate the molecular basis of that resistance in the population and design a field-applicable diagnostic assay for its monitoring.”
To that end, the researchers did a genome-wide comparison on mosquitoes that were fully susceptible to insecticides and Anopheles funestus mosquitoes from the Republic of Benin in Africa, which were resistant to DDT and the pyrethroid permethrin.
The team found the GSTe2 gene was upregulated in the resistant mosquitoes. And a single mutation (L119F) changed a non-resistant version of the gene to an insecticide-resistant version.
The researchers then designed a DNA-based diagnostic test for this metabolic resistance and confirmed that this mutation was found in mosquitoes from other areas of the world with DDT resistance, but it was completely absent in regions without resistance.
X-ray crystallography of the protein coded by the gene illustrated exactly how the mutation conferred resistance—by opening up the active site where DDT molecules bind to the protein so that more can be broken down. In other words, the mosquito can survive by breaking down the poison into non-toxic substances.
The researchers also introduced the gene into Drosophila melanogaster and found the flies became resistant to DDT and pyrethroids, whereas control flies did not. The team said this confirms that a single mutation is enough to make insects resistant to both DDT and pyrethroids.
“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,” Dr 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.”