As noted in a recent article by The Atlantic,1 history is rife with pest control experiments gone terribly wrong. Today the stakes are higher than ever, as scientists are increasingly turning to genetic engineering to affect environmental change.
Earlier this year, the Zika virus, which is carried by the Aedes aegypti mosquito, was declared a worldwide public health threat.2,3 Besides calling for increased use of chemical sprays against mosquitoes, focus quickly turned to the idea of releasing genetically engineered (GE) mosquitoes to control populations.
The male transgenic mosquitoes, which are released to mate with females in the wild, carry a “suicide” or “self-destruct gene” that gets transferred to the offspring, killing them before they reach breeding maturity.4
To achieve this, protein fragments from the herpes virus, E. coli bacteria, coral and cabbage looper moth were inserted into the insects. Biotech company Oxitec refers to their GE mosquitoes as a “non-chemical insecticide,” and these controversial creatures are now another step closer to being released on U.S. soil.
Florida Keys Community Is Latest Testing Ground for Transgenic Mosquito
Meetings for Key Haven residents have already been held to discuss Oxitec’s proposed GE mosquito trial in the area.5
In early March, the U.S. Food and Drug Administration (FDA) released a draft of its environmental impact study6 of the GE mosquito, declaring it will have “no significant impact” on the health of residents or the environment in this Florida Keys’ community.7
As noted by CNN, Zika wasn’t the original reason Oxitec’s transgenic mosquitoes were considered.
The Aedes aegypti mosquito also carries the dengue, yellow fever and chikungunya virus, and outbreaks of dengue fever in the Florida Keys in 2009 and 2010 prompted local mosquito control officials to look for more effective options to control the non-native insect.
According to Oxitec, field tests in Piracicaba, Brazil, led to an 82 percent decline to the mosquito population over an eight-month period.8 In the Cayman Islands, 96 percent of native mosquitoes were suppressed in a 2010 field trial.
The Cayman Islands recently approved full deployment of the Oxitec mosquito, starting in June, with weekly releases of hundreds of thousands of mosquitoes scheduled to continue for at least nine months.9
However, while the FDA has given the transgenic mosquito the thumbs up, Key Haven residents are not particularly keen on being guinea pigs.
Especially since neither dengue, Zika, or any of the other diseases spread by Aedes aegypti pose a threat to health in the Florida Keys.10 Mila de Mier, who lives in the small community of Key Haven, told CNN:11
“Less than a mile from the release site is a senior center and a local school. That area was not one that was affected by dengue. Not a single case ever. So why does the FDA want to do an experiment here when they can do this all over the world? …
There has been no acceptance from community members. If the local and federal government fail to protect us and our wishes, our last option will be to trust the judicial system and bring it to the court. A legal battle is an option at this point.”
What Could Go Wrong?
While decimating Aedes aegypti populations may sound like a good solution to eliminate transmission of disease, there’s always the potential for unforeseen side effects.
A 2011 article in The New York Times12 brought up a number of concerns, including the possibility that these genes might infect human blood, not through insect bites, but by finding entry through skin lesions or inhalation.
According to the Institute of Science in Society,13 such transmission could potentially create “insertion mutations” and other unpredictable types of DNA damage in the host.
Alfred Handler, Ph.D., a geneticist at the Agriculture Department in Hawaii has also pointed out that mosquitoes can develop resistance to the lethal gene. If such mosquitoes were to be released, the resistance could spread to the offspring.
According to Todd Shelly, an entomologist for the Agriculture Department in Hawaii, 3.5 percent of the insects in a laboratory test actually survived to adulthood, despite carrying the lethal gene.14
Another factor that could make the GE mosquito backfire is the fact that Oxitec’s mosquitoes were designed to die in the absence of tetracycline (which is introduced in the lab in order to keep them alive long enough to breed).
However, tetracycline and other antibiotics are showing up in the environment, in soil and surface water samples. The mosquitoes were designed with the assumption they would NOT encounter tetracycline in the wild. With tetracycline exposure (for example, in a lake) these insects could potentially thrive.
Last but not least, by employing so-called gene drive technology (which ensures that all offspring end up with the GE gene), concerns arise over the impact on biodiversity and the ecosystem as a whole.
Some argue that the extinction of the Aedes aegypti would hardly result in ecosystem collapse, and this may well be true. However, the Aedes aegypti is certainly not the only insect being genetically altered and released into the wild.
The larger problem lies in the fact that population scale ecosystem engineering is taking place without proper regulatory oversight, transparency, or public discussion. Decades’ old regulations are being relied on for these novel technologies, and they are sorely inadequate for the task.