Mutation Found in Resistant Mosquitoes

Science - AP ^ | 2003-05-12 | RICK CALLAHAN

[Junior]

Scientists have discovered the same genetic mutation in 11 types of West Nile- and malaria-spreading mosquitoes — a mutation that may explain their growing immunity to insecticides.

The findings could give chemical companies a molecular target for new insecticides to combat mosquitoes no longer kept in check by existing chemicals.

French scientists who discovered the mutation in the ace-1 gene said it appears to endow the mosquitoes with an immunity to two potent chemicals that cause a fatal paralysis in other mosquitoes.

Researchers from the University of Montpellier II, in Montpellier, France, found the mutated gene in 10 insecticide-resistant strains of the mosquito Culex pipiens, which spreads the West Nile virus (news - web sites) in Europe, Africa and the Caribbean.

They also found it in resistant populations of the Anopheles gambiae mosquito — which transmits the malaria parasite — that were collected in the Ivory Coast.

The scientists said the mutation in the ace-1 gene, which normally encodes a key enzyme targeted by some insecticides, makes the mosquitoes resistant to those chemicals.

The findings appear in the May 8 issue of the journal Nature.

Molecular biologist Mylene Weill led the Montpellier team in scrutinizing the genetics behind mosquito insecticide resistance, a problem that surfaced about 25 years ago and continues to grow.

Normally, insecticides containing either of two families of chemicals, organophosphates and carbamates, paralyzes and kills mosquitoes by blocking an enzyme that regulates nerve signals.

In the case of A. gambiae, its insecticide resistance has allowed malaria's deadly scourge to rebound in African nations where the parasite's courier was once controlled by spraying.

Since finding the mutation in 10 populations of insecticide-resistant C. pipiens, the researchers have found it in additional strains of that species, and expect to find it in others.

"We have looked at something like 15 resistant populations of C. pipiens and every time we've tested them we find the same mutation," Weill said.

While the findings are intriguing, much work remains to determine the precise genetic basis of mosquitoes' insecticide resistance, said Dyann Wirth, a microbiologist who directs the Harvard Malaria Initiative.

She said there may well be other genes that play a role in making the mosquitoes immune to many insecticides.

"I think it's a very good lead but there clearly needs to be more work done," Wirth said.

Dr. Joseph Vinetz of the University of Texas Medical Branch, chief spokesman for the Infectious Diseases Society of America, agrees. "Just finding a mutation, which is completely predictable, however, has no relation to the development of new insecticides."

Weill said she and her colleagues, whose discovery was aided by the recently mapped genome of the A. gambiae mosquito, are now collecting other resistant populations of the same species from Africa to test them for the same mutation.

She believes the same mutation may also be present in other insect pests, including those that eat crops.

Although malaria is primarily a problem in Africa and the developing world, a wild reservoir of the parasite was found last year in Virginia.

Weill said she hopes concern about malaria and West Nile — which killed 284 people in the United States — can convince chemical companies to devote more resources to new insecticides.

"Malaria is seen as an African problem, but with West Nile it's an American problem now," she said.

[Junior]

Ping.

[Chancellor Palpatine]

Here, let me be the first to say it - "Oh sure, you've proven microevolution, but did you have a videocamera running in order to record macroevolution? No? Well than, it never happened - the way I interpret my Bible tells me that".

[Aric2000]

Yeah, what he said!! LOL

[Doctor Stochastic]

Another favorable mutation.

[Finalapproach29er]

A very easy solution:

DDT!!!!! Limited use. It makes the egg shells of birds thin. The mother sits on eggs, they smash and die. But this was after extensive use of DDT. Limited use may be effective.

[Only1choice____Freedom]

I saw the movie X-Men, Are these X-Mosquitos?

[LiteKeeper]

bump

[Geritol]

The DDT studies were flawed. The thin shells of the eggs of birds of prey was first noted before 1900. During the 30 years of DDT use the populations of such birds actually increased.

[Aric2000]

Favorable for whom? ;)

[PatrickHenry]

Ping to the 2nd half of my list (Junior pinged most others).

[This ping list is for the evolution -- not creationism -- side of evolution threads, and sometimes for other science topics. To be added (or dropped), let me know via freepmail.]

[mewzilla]

Skeeters became resistant to DTT, too.

[visualops]

They have no chance against my rolled up magazine tho ;^)

[jennyp]

Yes, but it took them 20 years to do it. Since it's been 30 years since DDT hasn't been used, I'll bet the resistance to DDT has gotten significantly bred out of the gene pool (if not entirely) by now. If they could use DDT in a big way for 5 years & then rotate en masse to something different for another 5 years, they should be able to keep it in check, I'd think.

[f.Christian]

If I learn french that is evolution ... if I quit drinking --- that is evolution too !

[Doctor Stochastic]

For the mosquito, of course. It's their mutation.

[Aric2000]

Indeed, but BAD for us, we need to figure out how to put a stop to this evolution thing, it's gonna kill us ALL....

;)

[Dimensio]

For the mosquito, of course. It's their mutation.

Ah-hah! More proof that mutations are never beneficial!

[Lysander]

My bible does not mention mosquitoes. This must be the devils trick. Mosquitoes do not exist.

[Dementon]

They have no chance against my rolled up magazine tho ;^)

You just wait until they develop a defense against that...