January 2, 2009
New Solution To Mosquito Problem
Old mosquitoes are normally a catalyst in the spread of disease, so scientists from Australia have found a way to kill mosquitoes naturally by breeding them to carry an insect parasite that causes earlier death.
Until now, scientists had been searching for a way to genetically engineer mosquitoes to become resistant to illnesses like dengue fever and malaria.
When mosquitoes contract a disease like malaria or dengue, it takes two weeks of incubation before the insect can spread the illness to a human. This fact makes older mosquitoes more dangerous than young mosquitoes.
The Australian researchers infected a mosquito species with a fruit-fly parasite known to cut the fruit-fly lifespan in half. The scientists then bred several generations of the altered mosquito in a laboratory.
The researchers found that the mosquitoes born with the fruit-fly parasite lived only 21 days compared to 50 days for normal mosquitoes. The findings appear in the journal Science.
According to University of Queensland biologist Scott O'Neill, if the parasite spreads widely enough it "may provide an inexpensive approach to dengue control."
The bacterium, called Wolbachia, is very common among some mosquito types, so theoretically it could spread, noted the researchers.
O'Neill's team will begin longer studies next month to see how well the wMelPop strain can survive as more mosquitoes are born.
"By killing old mosquitoes, wMelPop could thus impact on dengue transmission," said Andrew Read and Matthew Thomas, Pennsylvania State University specialists, in an interview with the Associated Press.
The duo noted that there is a possibility that the dengue virus could evolve to incubate more quickly, although they believe this is less of a problem than the insecticide resistance they are seeing in mosquitoes.
"Determining whether it can remove enough infectious mosquitoes to be useful will be a challenge," they added.
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