Building a better mosquito


By ERIC BERGER
Copyright 2007 Houston Chronicle

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Scientists have taken a significant step toward creating genetically modified mosquitoes that could one day wipe malaria from the planet.

Tinkering with the genes in mosquitoes, the researchers have created new breeds of the insect that are resistant to malaria, the fourth-leading cause of death in young children worldwide.

And for the first time, in a lab at least, they have shown this new type of mosquito can breed and compete more efficiently than natural mosquitoes, suggesting the modified, or transgenic, type could spread in the wild.

The scientists, based at Johns Hopkins University in Baltimore, aren't yet ready to unleash their mosquitoes. But the new study, published in today's issue of Proceedings of the National Academy of Sciences, may ease doubts about whether transgenic mosquitoes can survive.

A definitive test could only take place in the field. Whether populations afflicted by malaria, primarily in sub-Saharan Africa, would accept such an intervention remains questionable.

"We could never consider doing anything without the consent of the affected population," said Marcelo Jacobs-Lorena, lead author of the study. "But I think that is something we could work with them to achieve over time."

According to the U.S. Centers for Disease Control and Prevention, between 350 million and 500 million cases of malaria occur worldwide each year, killing more than 1 million people.

Scientists and public health officials have looked toward genetically modified mosquitoes because, with a ban on the pesticide DDT, they have few other options in the developing world for controlling mosquitoes and the diseases they spread.

"This is an important step," said Craig Coates, an entomologist at Texas A&M University who is working to develop transgenic mosquitoes that would inhibit the spread of yellow fever.

Previous efforts to modify the genetics of mosquitoes generally have led to less effective breeders, leading some scientists to suggest it won't be possible to create competitive transgenic mosquitoes. But Jacobs-Lorena and colleagues combined equal numbers of transgenic and wild mosquitoes in a cage, letting them feed on malaria-infected mice. After nine generations, 70 percent of the mosquitoes were transgenic and just 30 percent wild.

There were limitations. Not all mice in the wild are infected with malaria, so if the transgenic mosquitoes were advantaged by being resistant to the disease, it's unclear how much of that advantage would translate into the field.

Coates said tests more similar to real-world conditions could take place within the next few years as scientists continue to perfect their transgenic bugs.

But he acknowledged that a monumental debate awaits. Genetically modified foods, such as tomatoes and potatoes, are controversial enough. Work with genetically modified animals so far has largely been restricted to husbandry.

Breeding a new type of mosquito for release probably would ratchet up the debate, said Scott Weaver, director for Tropical and Emerging Infectious Diseases at the University of Texas Medical Branch's Center for Biodefense and Emerging Infectious Diseases.

"It's very hard to imagine that any government would accept the release of transgenic mosquitoes in their backyard," he said. "The tendency of people is to want to kill mosquitoes, not help them propagate."

Perhaps the biggest problem is that no one will be able to anticipate the consequences of releasing a new breed of mosquito into the wild, said Rudy Bueno, director of Harris County's Mosquito Control division.

Malaria isn't significant in the United States — there are about 1,000 cases a year, and most of those are in people traveling from tropical areas where the disease is a problem.

But mosquitoes in Harris County carry other diseases, such as West Nile. Current methods to control the spread of mosquitoes, primarily surveillance and the spraying of approved pesticides in areas where infected bugs are found, work pretty well, Bueno said.

That doesn't mean more deadly diseases won't come. West Nile virus spread across the country in a handful of years. For that reason, Bueno said, it's beneficial for science to at least consider the use of transgenic mosquitoes as a weapon in the bug battle.

"Anything that has the possibility of enhancing the public health is worth exploring," he said.

eric.berger@chron.com

why not a mosquito that drinks water or tree sap instead of blood?

Or a Mosquito that eats only other mosquitoes.... They could eat themselves into extinction!!

FB

Those transvestite mosquitoes may be the answer.

You guys crack me up! I was thinking the same thing... Why tinker with something to make it 'better' when you can rid the planet of them pesky bastards!

its like saying we've modified the serial killer gene so they will only kill one time...

There are some strains of Malaria that are resistant to the most common drugs. I can't envision the new mosquito breed wiping out malaria.

Malaria will simply eventually mutate to infect the new breed. Could end up be the worst strain of malaria yet.

Some of you may remember screw worms. They were the larvae of blow flies. The fly would lay eggs in the flesh of a wound and the larvae (maggots) would eat the live flesh eventually killing the animal. Screw worms devastated wildlife in the warmer climes of North and South America and were the bane of cattlemen. I can remember as a kid, putting cattle in the chute and digging the maggots out of deep wounds and then treating the wound to kill those I may have missed.

Texas A&M studied the blow fly and determined that the flies mate only once in a life cycle. The scientists began sterilizing male blowflies with radiation and dropping them out of airplanes in small wooden boxes throughout the habitats. ultimately, screw worms in the areas where the sterile flies were dropped were eradicated in a few short years.

Of course, Africanized Bees are the product of another effort to "improve" mother nature that went awry.

You never know.

I just don't know fellas. While I do agree that the scientists are on to something here, I have concerns of what this could potentially lead to down the road. Science is a marvelous thing when applied in the right way. But Nature has a long standing habit of biting us very hard every time we tinker with her and I shudder to think of what havoc a genetically improved, highly aggressive strain of mosquito might be capable of if this experiment turned the wrong direction and the diseases we're trying to eradicate suddenly found a way around our cure. That has happened before and I fear it may happen again if Science isn't careful about this one.

Mosquito’s and tsetse fly’s done more to preserve wild animals and habitat then any conservation organization has ever done!
If I would not for them there would be nothing left in Africa to hunt for you.

Say thanks to the little bastards!

Talking about introduced species reminded me of a story I heard.

Some years ago St Petersburg had a serious pigeon problem, so someone in their infinate wisdom decided to introduce a predator. In this case it was the siberian crow. This bird has a wingspan of some 6' so is huge.

Anyway they did the job and cleared up the pigeon quite effectively. The problem was three fold tthough;

1) when the pigeons ran out they started eating peoples cats and small dogs instead.

2)They were so big that they were a little lazy so they started using the minarettes as launching ski slopes by sliding down them to take off. This scratched off much of the gold leaf that was used on the buildings!!

3) Finally with the shiny tops on the buildings the crows were dropping rocks onto them and causing heaps of damage, as this was their usual way of getting water when lakes froze over in their home ranges!!

Needless to say the Crows were got rid of qquite rapidly!!

FB

For the nonbug guys, there are mosquitoes that eat other mosquiotes, they are of a group called Toxirhynchites (that spelling is close, but not right, I never could spell). They lay their eggs in containers. They especially like tires. They eat other mosquites in the larval stage, but they are not very competitive. We could never get enough in an area to make a really big impact on overall populations. Dealing with mosquitoes is like federal budget numbers, reducing a billion here and there does not make a big effect on the overall number. This development could actually make a difference. When they brought up the idea a few years back, I had doubts that they could pull it off. The mechanics of the process seemed too complicated. If it works, it will relieve a lot of pain and suffering. As Texas Hunter says, it worked for screw worm, and has worked for a number of other less famous cases. Let's hope it works here.

quote:

Mosquito’s and tsetse fly’s done more to preserve wild animals and habitat then any conservation organization has ever done!
If I would not for them there would be nothing left in Africa to hunt for you.

Say thanks to the little bastards!

- posted by freischuetz

By killing millions of natives?

quote:

Originally posted by Hunter Formerly Known As Texas Hunter:

quote:

Mosquito’s and tsetse fly’s done more to preserve wild animals and habitat then any conservation organization has ever done!
If I would not for them there would be nothing left in Africa to hunt for you.

Say thanks to the little bastards!

- posted by freischuetz

By killing millions of natives?

By making some areas hostile / unhealthy for settlement and development!

Normally the indigenous population is very little affected by the local strains of malaria!

Today more of the people die “ on malaria†because their immune system is not function or weaken from other secondary / primarily sicknesses. (HIV)

We do not like to hear it, but if there would be no death by famine / drought/ disaster/ wars/ epidemics occurred in the last 4000 years do you think this planet would still support life?

We all talking about elephant hunting and overpopulation of this species in Zimbabwe, Botswana and South Africa we talking about and seeing the distraction to their habitat once the carrying capacity is exceeded!

To help protect this elephants from self-destruction we hunt them? At least that is an often-stated argument!

What are you going to do if the human population exceed carrying capacity?? And if humans carry on in the same way it will happen sooner or later.

The results are a population crash far below the original carrying capacity sometimes close to or total extinction!

It is cruel but is a fact that is how nature controls and protects itself.