With the Zika virus making headlines around the world and sparking fears of a global public health crisis, scientists are exploring every possible avenue that might help stem the spread of this severe, mosquito-borne illness (as well as the equally serious diseases of dengue fever, yellow fever, and the chikungunya virus, which are also spread by mosquitoes). The latest weapon in the fight against Zika is certainly a controversial choice, but it may also be the most effective solution possible: genetically modified mosquitoes. This is the proposal from biotechnology firm Oxitec, which is currently attempting to implement a field trial in the Key West, Florida, region to test the disease-fighting powers of its GM mosquitoes.
The plan is relatively simple. Oxitec has genetically engineered mosquitoes to contain a gene that will be lethal for their offspring (more specifically, the mosquitoes have been engineered to survive only in the presence of the antibiotic tetracycline; if they do not have access to tetracycline, these GM mosquitoes will die). After being raised to adulthood in a lab, the male GM mosquitoes (which do not bite, and therefore cannot transmit disease) are released into the local mosquito population, where they mate with wild females. Because of the altered DNA they inherit, the next generation of mosquitoes is unable to survive to adulthood, and so they die off, causing the mosquito population to shrink.
It’s a proposal that has many appealing aspects, including greater precision than many other pest-control techniques, and a potentially limited need for chemical insecticides. However, it has also raised many questions. To get a better understanding of this project and its implications, read on for answers to some of the most frequently asked questions about GM mosquitoes, and their possible use in the Florida Keys field trial.
Are GM mosquitoes sterile?
Oxitec’s mosquitoes are not sterile because the altered DNA impacts the mosquitoes’ offspring rather than the mosquitoes themselves; in other words, the mosquitoes must be able to produce offspring in order for the genetic modifications to produce the intended result.
Will only male GM mosquitoes be released?
The plan is for only male GM mosquitoes to be released into the environment, in order to avoid introducing even more biting and potentially disease-transmitting females into the local population, but the male-female sorting process cannot be guaranteed to be fully accurate. There is therefore a chance that a small fraction of the released insects could be female.
Could GM mosquitoes bite humans?
If there are female GM mosquitoes among the insects released into the environment, then humans could potentially be exposed to bites. The likelihood of being bitten by a GM mosquito as opposed to a wild mosquito would depend on a number of factors, including the rate of accidental release of GM females and the number of wild mosquitoes already in the area.
Are GM mosquito bites dangerous?
A non-modified mosquito bite injects about 40 proteins into human skin; female GM mosquitoes could theoretically introduce two additional proteins (which are found in the mosquito’s salivary gland). No studies have yet been conducted to determine if these proteins pose a risk to human health, or even if they are in fact injected into humans through a bite, but the probable conclusion is that GM mosquito bites are not likely to be harmful to humans.
What impact do GM mosquitoes have on the environment?
It is difficult to predict what effect the introduction of GM mosquitoes may ultimately have on the environment. The environmental risk that poses the most immediate cause for concern is that a decline in mosquito populations brought about by the success of the field trial would leave an ecological niche that could potentially be filled by other, even more harmful, pests. However, after initial review, the US Food and Drug Administration (FDA) released a Preliminary Finding of No Significant Impact regarding the Florida Keys trial, which concluded that the trial would not result in significant environmental impact.
Will GM mosquitoes eliminate dengue fever from the Florida Keys?
GM mosquitoes have demonstrated the promise of drastically reducing dengue fever; in 2013, Oxitec reported a 96% suppression of the dengue mosquito during a trial carried out in the village of Mandacaru in Brazil. However, this may not be enough to completely eradicate the spread of dengue, because it is possible for the dengue mosquito to transmit the disease even at very low population levels.
Who would regulate the GM mosquito release in the Florida Keys?
Several agencies would be involved in the regulation of the Florida Keys field investigational trial. The FDA would approve the trial, and the U.S. Department of Agriculture would be responsible for approving the import of mosquito eggs into the US. The field trial application will also be reviewed by the Centers for Disease Control and Prevention and the Environmental Protection Agency, and an environmental assessment will be made available for public comment.