As seasons shift and Zika-related news dwindles in the media, it’s easy to lose sight of what a serious and present threat mosquitoes can pose to public health. However, at this very moment, researchers are virtually wiping out entire mosquito populations in several locations around the globe in an effort to quell the spread of diseases such as Zika and Dengue. And this November, as Scientific American reports in the latest issue, residents of Key Haven, Florida, will vote on whether to allow a new trial involving genetically modified insects to go ahead in their community.
While many similar trials are already completed or ongoing in other states, this would be the first time actual mutant mosquitoes are released in the U.S. Oxitec, the biotech firm pushing for the trial, has previously released GM mosquitoes in various spots throughout Central and South America without causing any negative health effects, but some Key Haven residents remain uncertain about the idea.
Perhaps a good way to address fears around such experiments is to take a closer look at the history and science surrounding them. So, first of all, where and when have similar experiments already taken place, and what were the results? Answers to these questions are revealed in the graphic below. I, for one, had no idea just how many of these trials were going on over the past few years! But given their success rates, I expect they will increase in size and scope going forward.
So, modified mosquito trials have been surprisingly numerous and largely successful thus far. But how do these experiments actually work? Let’s start with the idea of of altering mosquitoes’ DNA. The graphic below, first published in the November 2011 issue of Scientific American, breaks down the science of one technique developed by Oxitec back in 2002. The method they currently use is different, but still relies on genetic modification to kill mosquitoes off over time.*
Oxitec is the only program currently using GM mosquitoes, so what are the other research groups doing instead? The following graphic, also from the Scientific American archive, shows how the program known as Eliminate Dengue has been infecting mosquitoes with special virus-resistant bacteria in order to stop them from spreading disease.
Using Wolbachia bacteria is a common theme among the non-GM mosquito programs. Eliminate Dengue’s method seeks to replace the existing population rather than diminishing it. The other trials use a different type of Wolbachia to prevent fertilized eggs from hatching, thus greatly reducing the number of mosquitoes in the community.
While evidence indicates that modified mosquitoes—mutant or otherwise—pose no threat to human health, I do wonder how wiping out entire mosquito populations might effect ecosystems over time. So perhaps programs like Eliminate Dengue represent a better approach. While these trials have been relatively small thus far, only effecting rural communities, Eliminate Dengue is about to ramp up their work by releasing Wolbachia-infected mosquitoes in large, urban areas of Brazil and Colombia. This new venture may offer new revelations about the potential of modified mosquitoes to positively impact public health.
*Editor's Note (10/31/16): This paragraph was edited after posting to clarify its content as well as correct an error.