This year will be a bad year for mosquitoes. Actually, it will be a GREAT year for them. It will be a bad year for US. Get ready for a whole new threat.
Mosquitoes inherit DEET resistance
Genetic trait explains how some insects are unaffected by powerful repellent.
A blast of DEET deters some - but not all - mosquitoes from sucking human blood.
Research
The indifference of some mosquitoes to a common insect repellent is due to an easily inherited genetic trait that can be rapidly evolved by later generations, a new study suggests.
By selective breeding, James Logan and colleagues at Rothamsted Research in Harpenden, UK, created strains of Aedes aegypti mosquitoes in which half of the females do not respond to DEET (N,N-diethyl-meta-toluamide) — a powerful insect repellent. They suggest that this rapidly evolved insensitivity is due to a single dominant gene — one that confers resistance even if the trait is inherited from only one parent.
The researchers have not identified the gene that they propose is responsible for DEET resistance, or precise details about its workings. They did, however, find a type of odour-sensing cell that responds to DEET in most mosquitoes but is less sensitive to the repellent in the resistant ones. Their findings are reported today in Proceedings of the National Academy of Sciences1.
"That there might actually be a gene lurking in the background in mosquitoes that causes DEET resistance is the single most surprising result," says Leslie Vosshall, who was not involved with the study and who investigates the neural and genetic basis of odour perception in mosquitoes at the Rockefeller University in New York City. "This hasn't really been reported before."
Propagating pests
Aedes aegypti is a species of mosquito that causes yellow fever, dengue fever and other viral diseases. Its blood-sucking females are not all cowed by DEET: around 13% of the laboratory populations tested by Logan's team would land on human arms covered in the repellent.
Researchers had previously found weak evidence that DEET resistance could be inherited in these mosquitoes, says John Brookfield, a coauthor of the paper and a geneticist at the University of Nottingham. But after picking out the DEET-insensitive females, the team found that in a single generation of breeding with untested males, they could create a strain where 50% of the females did not respond to DEET. That proportion remained relatively stable across subsequent generations of selective breeding.
This fast pickup and later stability suggests that a single gene, rather than an aggregation of multiple genetic traits, is key for DEET detection, Brookfield says — at least, in the population the researchers studied. And when the nonresistant mosquitoes were later mated with the resistant population, around half of their offspring were insensitive to DEET — suggesting that the gene is dominant. A previous study on the fruitfly, Drosophila melanogaster, had found that a nondominant trait could lead to inherited DEET resistance.
Insensitive types
Trying to narrow down what the gene could be doing, the researchers focused on the odour-sensing cells found in antennae, which are known to detect DEET and other chemicals. Though some studies have suggested that DEET works by jamming neurons that sense human odors, others have picked out neurons which seem to specifically respond to DEET.
The team found that odor-sensing cells in general were less sensitive to DEET in resistant females compared with cells in nonresistant females. But they also spotted one type of neuron that showed distinctly lower responses to high DEET concentrations in the repellent-insensitive females. Any gene responsible for this effect might alter that cell so that it could not recognize DEET or it might mutate an odorant-binding protein that delivers DEET to a receptor, the team speculates.
Vosshall says that the study shows there is a genetic basis for sensing DEET but it doesn't resolve how the resistance works. "What remains to be shown is a causal link between the effects on the antenna and insensitivity to DEET," she says. The authors excluded from their analysis one set of neurons that were missing in insensitive mosquitoes, she points out, which could explain why they could not sense DEET.
Whatever the molecular mechanisms involved turn out to be, the study further affirms that repellents like DEET may lead to resistance over time if used to control mosquito-borne disease on a large scale, says Logan. He next wants to test the evolution of DEET sensitivity using wild populations of mosquitoes, including those that spread malaria. "We're not saying that repellents shouldn't be used," he says. "But we have to understand how they work before we can use them properly." -- pulled from www.nature.com/news/2010/100503/full/news.2010.216.html
Mosquitoes can develop an immunity to DEET and breed offspring that are also impervious to the bug repellent, scientists in England report. Female mosquitoes use their antenna to zero in on humans in their hunt for blood to fertilize their eggs. DEET is believed to interfere with their ability to smell. A DEET-resistant mosquito would still be able to detect the savoury human smell it’s looking for. “There is something in the antenna they use to smell that reacted differently,” Dr. Nina Stanczyk of Rothhamstead Research, the largest agricultural research center in the U.K., told the Star on Tuesday. Scientists studying mosquitoes in a laboratory realized some “weren’t detecting the smells of DEET.” When researchers bred those mosquitoes, the new generation could smell through the DEET as well. DEET, developed in 1958, is little understood but highly effective in repelling mosquitoes. “There’s been an awful lot of research on this subject” of repellents, said Stanczyk. “This could give us a greater understanding of how DEET works and how to develop new repellents.” Stanczyk cautions that her research is limited to a laboratory, although she’s keen to extend it to field work. Outside of a laboratory, the only ideal breeding ground for DEET-resistant mosquitoes would be somewhere that everyone was wearing the repellent, she said. Researchers also studied only one species of mosquito, the yellow fever and dengue-carrying Aedes aegypti. Canada, Bermuda, Chile and Uruguay are the four countries in the Americas not infested with A. aegypti. “This research is very interesting but we don’t think it will lead to a worldwide failure of repellents,” she said. “People should keep protecting themselves so they don’t catch diseases.” The findings are published in the May 3 edition of the journal Proceedings of the National Academy of Sciences. -- pulled from http://www.thestar.com/news/world/article/807800--scientists-breed-deet-resistant-mosquitoes
I have done my own experiments and have reaped the same results. By dosing different groupings of mosquitoes with different amounts of DEET and then breeding new generations that resist more and more DEET, I was able to produce mosquitoes that were completely DEET proof.
The DEET resistance combined with the abnormally warm winter that most of this country has experienced this year will surely mean a 'biblical plague' like amount of mosquitoes in the coming year.
I truly believe this year's warm winter was a direct result of government weather control by use of the HAARP station. The warm winter, which has permitted the survival of HUGE numbers of mosquitoes, combined with the genetic enhancement of DEET resistance, will surely profit the chemical companies which, as we all know, along with the oil companies, are the U.S. Government's largest financial supporters. But THAT is a different blog. Coming soon.
Blackguard.
