In Oxitec's mosquito factory on the outskirts of Oxford, England, scientists use razor-sharp glass needles to inject small amounts of DNA into tens of thousands of mosquito eggs. Most of the eggs will die, but the ones that survive will incorporate the extra DNA into their genome and go on to develop two genetic modifications that can be passed down. The first causes the mosquitoes to glow fluorescent red when placed under a high-powered microscope. Though it might sound like something from a Michael Crichton novel, it's a relatively old trick that's used to track all types of research animals. The second modification, the insertion of an autocidal gene, is what causes the mosquitoes to self-destruct.

In the lab, the modified mosquitoes are fed tetracycline. This common antibiotic essentially turns the death gene off. It allows the insects to stay alive, breed, and produce eggs that now contain the gene.

"All the fancy genetic stuff is done over [in England]," Doyle explains. "I call Oxitec, they send a boxful of eggs, we grow the eggs in cake pans, give them food and water, and sort them in a lab we'll set up in a trailer."

Aedes aegypti is the only species of mosquito in South Florida capable of spreading dengue fever.
Photo courtesy of Oxitec
Aedes aegypti is the only species of mosquito in South Florida capable of spreading dengue fever.
Oxitec's genetically modified mosquito larvae glow fluorescent green and red so researchers can track them.
Photo courtesy of Oxitec
Oxitec's genetically modified mosquito larvae glow fluorescent green and red so researchers can track them.

By sorting, Doyle means weeding out any females by looking at the size of the larvae — males are smaller than females. It's the most crucial step in the process because only female mosquitoes bite humans, and releasing hordes of modified mosquitoes capable of sucking our blood would be counterproductive at best. Doyle acknowledges, however, this sorting method isn't foolproof; about one female gets through and is released for every 1,500 male mosquitoes, he says.

"The chance of getting bit by a female genetically modified mosquito is pretty small, but it's not impossible. It's going to happen." The effects of such a bite are unclear, but the idea of getting bitten by a mutant mosquito could freak people out. Environmental groups and organizations opposed to genetic modifications of any sort have been vocal over the lack of information on this aspect. Oxitec maintains that the proteins composing the genetic modification aren't present in mosquito saliva and thus won't be transmitted during a bite. It's a sentiment that scientists who are critical of the company tend to agree with.

Doyle and his team are now busy looking for two similar six-block-by-six-block areas in Key West where they can conduct their experiment. In phase one, they intend to release a few thousand Oxitec mosquitoes and set traps. From the mosquitoes that are caught, they can determine the ratio of Oxitec mosquitoes to normal ones. Then they'll do a second phase, releasing ten Oxitec mosquitoes for every wild one. Doyle says that over six months, 2 million to 6 million genetically modified mosquitoes will be released. Saturating the test site with the modified mosquitoes should increase their odds for successfully mating with normal females.

A potential pitfall is that the street-smart, wild males will simply outgun the lab-pampered mosquitoes. But if all goes as planned and Oxitec mosquitoes reach the females first, the offspring will hatch and live for a few days before the genetic modification kicks into effect and shuts down the cellular machinery needed for the pupae to become functioning adults. Hordes of tiny mosquito corpses will flow through the shallow breeding grounds.

Doyle is well aware of the experimental nature of a release and says he needs to be a "cautious buyer." At the same time, he's eager to get the test under way because the threat of dengue looms as millions of tourists flock to the Keys each year.

When Joel Biddle, Mila de Mier, and their Conch friends began looking into Oxitec's history, they found a few worrisome things about the decade-old, privately funded company. Oxitec, which employs about 40 people, has consistently come under fire from environmental organ­izations, anti-GM groups, and academics for its lack of transparency when carrying out experiments. So far, the company has released mosquitoes in Brazil in 2011, Malaysia in 2010, and the Cayman Islands — where more than 3 million genetically modified mosquitoes have been dispatched since 2008.

Few peer-reviewed scientific journal articles have been published demonstrating the effectiveness and safety of genetically modified mosquitoes when released in the wild. Articles that have been published include an Oxitec staffer among the authors, and there are no independent, third-party studies under way.

Opponents, including the Conchs at the real estate office, hone in on the Cayman experiment because it's the furthest along. About four years ago, Oxitec and the Cayman mosquito control authority collaborated on an experiment without providing much information to the scientific community or local residents about the release. In November 2010, Oxitec took the stage at a medical conference in Atlanta and delivered findings from what was the first field trial of genetically modified mosquitoes. Some researchers in the crowd were surprised that, all of a sudden, a British biotech company was announcing it had released its mutant mosquitoes in the wild without consulting the larger research community.

In response, the prestigious journal Science published a news article that took a biting tone as it questioned whether the company had rushed to release its mosquitoes in the Cayman Islands, and suggested that the hastiness and off-the-radar style of the experiment had strained Oxitec's ties with funders, including the Bill & Melinda Gates Foundation. This past January, researchers at Germany's Max Planck Institute published a paper in the journal PLoS Neglected Tropical Diseases implying that Oxitec exploited a weak regulatory environment in the Cayman Islands to do the experiment with minimal oversight and little effort to inform the locals that millions of genetically modified organisms were being let loose in their back yard.

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7 comments
Yuwfhan
Yuwfhan

i have not read these articles and i don't claim to know all the facts. You have made the argument that these methods are effective, but are they cheap, pheasible, and most are they safe for other species and the environment. if these mosquitoes are treated with the bacteria is there possibility of this bacteria spreading through a mosquito bite, and if it does will they even have an effect on the bite victims. just wondering

Guest
Guest

There are several cheap, effective and environmentally friendly alternatives to GM mosquitoes. Native plants that repel Aedes aegypti like American Beautyberry can be used as screening to reduce the House Index. A study using repellent plants in Tanzania reduced all mosquitoes found in houses by 50%, the cost was $1.50 per house which includes maintenance and labor costs. This can be used with attractants and lethal ovitraps using used coffee grounds or other cheap environmentally friendly larvicides, as well as fan traps on the lethal ovitraps to not only reduce the larvae survival but also catch the adult females. This push pull method may not only reduce the larvae from surviving, but unlike GM mosquitoes will also target the adult females and reduce the chance of Aedes aegypti entering the home, and at a fraction of the cost.

Other methods include the use of some strains of the fungi Beauveria bassiana and Metarhizium anisopliae which some peer reviewed studies suggest can also reduce the survival of Aedes aegypti offspring, but unlike GM mosquitoes can also cause mortality in the adult females, thus reducing both the population and the chance of being bit.

Yet another example is use of the bacteria Wolbachia, which some peer reviewed studies suggest may reduce the adult Aedes aegypti lifespan by 50% and unlike GM mosquitoes may actually provide resistance against dengue serotype 2 and chikungunya. There are several other alternatives as well.

What Mosquito Control has failed to mention is that releasing millions of GM mosquitoes including thousands of females could potentially increase the risk of transmitting mosquito-borne diseases. Releasing millions of male mosquitoes may also increase the risk of chikungunya which a peer reviewed study suggested can be spread when Aedes aegypti mate. With each male mating as many as 21 times in their lifetime that is a huge risk not worth taking unless the adult female lifespan is significantly reduced or there is resistance against chikungunya, which doesn't appear to be the case for GM mosquitoes. There have been over 100 cases of chikungunya reported in the U.S. between 2006 and 2009 including cases in Florida, so this a very real risk. Florida entomologist Walter J. Tabachnick, estimated that if an outbreak that occurred in Italy had occurred in Key West it would have caused 1,200 cases of chikungunya and 4,000 cases if it occurred during tourist season. The Beauveria bassiana and Metarhizium anisopliae alternatives both reduce the lifespan of the adult female and therefore reduce the chance of chikungunya spreading, they can also be used without releasing more males but instead infecting the already existing males and/or females. The Wolbachia alternative may reduce the lifespan of adult female Aedes aegypti and may even provide resistance against chikungunya, so even if more males were released there would be a significantly reduced risk of spreading chikungunya compared to GM mosquitoes.

There are numerous unknowns such as whether or not the synthetic protein based on sequences from E.coli and the Herpes simplex virus that the GM mosquitoes express could be transmitted to humans during a bite or affect animals ingesting them. As well as a partially independent lab reporting 15% of the GM mosquito offspring surviving in the presence of chicken found in cat food and a member of the mosquito control district admitting that Aedes aegypti have been found breeding in pet dishes, making such an event likely if GM mosquitoes are released. Along with Florida Medical Entomology Laboratory's Phil Lounibos stating there is no supporting background evidence that GM mosquitoes would solve a dengue problem. All of this and more makes a GM mosquito release seem like an expensive, pointless and potentially risky proposal.

mariela fajardo
mariela fajardo

Dengue is an infection produced by those arthropods (mosquito) who have in their prosboscis the disease infecting each host when they are bite by the insect, at least of thousand of cases is seeing all around of USA and the problem it is not only with the A. Aegipty, because we need to realize that in California, in St. Louis it is a common the encephalitis produced by the bite of the mosquito , the Aedes Gambia, Culex Pipiens Quinquefasciatus, Culex Pipiens Pipiens, Culex Nigripapuls, and arthropodo-borne viruses (arboviruses) it is a problem that concern all the community in general, and the CDC needs to take a inmediately decisions to prevent the spread of this virus infections, the same with the colaborations of those companies that have the chemical to remove the large population of mosquito and prevent their offsprings,(progeny) to grow and the transmission of the disease to a large populations,

Budgielover
Budgielover

I don't know about this. Mosquitoes are at the bottom of the food chain, and while they're detrimental to humans, they're a very important part of the ecosystem, eaten by birds, fish, and bats. They also help pollinate crops and plants. While people do not need mosquitoes, they love birdwatching and fishing, two things that may be impacted severely. This experiment may not be too harmful to the environment if it's only going to kill one species of bug, but it it definitely not something to be taken lightly. If there's complications, the ramifications could be enormous. Why not take some time to get third-party analysis and opinions from other environmental experts?

Jason
Jason

Every time I hear "genetically modified" it gives me the creeps. Remember Africanized bees? We may end up with mutant mosquitoes the size of pidgeons, and Key West residents still suffering from Dengue fever. By the way Natasha Marie, I demonize ALL mosquitoes. They are a pain in the a.. when you try to do anything outdoors in the summertime. I'd be willing to pay a pretty-penny for any device that would kill ALL the mosquitoes in a radius of 100 yards when I'm out in the yard. They can have the Everglades...

Natasha Marie Agramonte
Natasha Marie Agramonte

Fair and thorough analysis of this topic that isn't so quick to demonize GM mosquitoes like many people that don't understand the science are apt to do. Also addresses some of the valid concerns of Key West residents and responses to some of those concerns from mosquito experts, some of whom I'm personally familiar. Overall, an excellent article with few mistakes (only one that I caught ... Aedes aegypti is the not only species of mosquito in South Florida capable of spreading dengue virus, but it is the primary vector species in that area)

 
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