Published on 31 Mar 2012 Sections ,

Florida frontline for new GM mosquito tests?

Science Editor

A UK company has developed a strain of genetically modified mosquito that could drastically reduce diseases like dengue fever. But are Florida’s residents prepared to trial the GM insect in Key West?

The tourist haven of Florida’s Key West may soon be playing host to a totally new kind of visitor: genetically modified mosquitoes, engineered in a British laboratory to prevent the spread of tropical disease.

The technology has the potential to control deadly mosquito-borne diseases like dengue fever, without the cost and ecological damage that results from using insecticides. But as with any GM technology, opponents warn the insects could do far more harm than good.

A plan to introduce the insects to this southernmost point in the continental United States promises to make it the frontline in a new test of the public’s acceptance of genetic modification.

Currently the authorities in Key West, like mush of the southern United States, spend millions each year controlling mosquitoes. A particular concern is the yellow fever mosquito Aedes aegypti which can spread sometimes deadly dengue fever virus.

Dengue is largely confined to the tropics where it infects more than 50 million people each year. For most it causes a severe and painful fever, but around 25 thousand people die annually, many of them children.

In 2009 Key West had a minor dengue outbreak that coincided with the emergence of resistance to insecticides among local mosquitoes. Concerned about the impact of a future dengue outbreak on tourism, authorities looked to the new GM mosquito being developed by a small Didcot-based start up, Oxitec.

Read more: GM mosquito battles dengue fever

‘Stealth bomber’

The idea is based on a tried and tested method of insect pest-control: sterilisation. A gene is inserted into the mosquitoes that when it is expressed in the following generation, causes the developing offspring to die.

In the lab, the gene is kept silent by an antibiotic added to the insect’s food. But in the environment, in the absence of antibiotic, the gene is activated. Oxitec’s strategy is to release only male mosquitoes which do not bite humans. If enough are released, all the wild female mosquitoes will breed with the engineered ones. The company claim a field trial in the Cayman Islands in 2010 reduced the dengue mosquito population by 80 per cent.

Some people call it playing God. I call it good management. Dr Michael Doyle

“It’s like the smart bomb or stealth bomber of mosquito control,” says Dr Michael Doyle, director of the Florida Keys Mosquito Control Authority. Aedes aegypti is notorious for avoiding insecticide sprays and other control methods. It can breed in tiny amounts of standing water often in gardens and under homes. Because the GM mosquito targets others, it gets around that problem, he said.

As a result, it has less impact on other insect species. “You can go in and remove the species that are bad and allow the species that may have no effect on humans to play out their role in the environment,” he said. “Some people call that playing God. I call it good management,”

Potential risks

But others don’t see it that way. Anti-GM campaigners have already begun to mobilise opposition in Key West. “Oxitec is a company that is pushing ahead to commercialise this technology without really doing a thorough risk assessment or properly engaging the public in the potential risks,” says Dr Helen Wallace of Genewatch.

Oxitec is pushing ahead to commercialise this technology without really doing a thorough risk assessment. Dr Helen Wallace, Genewatch

Campaigners like Wallace argue Oxitec haven’t properly informed people about the potential for risk of releasing female GM mosquitoes, or evidence that some offspring do survive the fatal effects of the inserted gene.

They are also concerned about whether antibiotics in the environment could allow some mosquitoes with the gene to survive. That presents the possibility of engineered mosquitoes biting someone, or the released mosquitoes evolving resistance to the gene supposed to kill them.

They accuse Oxitec of moving too fast with the technology before these questions have been addressed.

Read more: A brief history of GM

Safe, sustainable and beneficial?

The company’s CEO, Hadyn Parry, strongly defends his company’s technology as safe and well-studied, arguing it will be independent scrutiny that ultimately decides whether it goes ahead or not. “It’s up to us to prove our case, and its up to the regulators to deem whether our case is safe, sustainable and is likely to prove a benefit,” he said.

In his view, a vocal minority could delay poorer countries a technology that has a real chance of helping them. “You’ve got 50 to 100 million getting dengue each year with symptoms, severity and geographic spread all getting worse – how slow does anyone want us to go?” The company is already conducting field trials in Brazil and is in talks about others in Panama and Malaysia.

You’ve got 50 to 100 million getting dengue each year. How slow does anyone want us to go? Hadyn Perry, Oxitec

The authorities in Key West want the US regulator to rule on the mosquitoes within the next year. One current obstacle is that no regulatory body has jurisdiction over a technology as new as a genetically modified biting insect.

If the US regulator does decide to give a green light to lab-engineered mosquitoes, however, it would set an important global precedent. The US regulator has international recognition and its decisions are often accepted by other countries. That would likely help Oxitec to move into more dengue-affected countries in Asia and South America.

But if they say no, critics fear it could be more than a setback for Oxitec. Advances in lab-engineered insects to control other, even more important diseases like malaria could be delayed by decades, they say.