Using Mosquitoes to Wipe Out Mosquitoes

Aedes Aegypti, a major form of transmission of many deadly diseases. Source

When was the last time you were bitten by a mosquitoe? If you are in a tropical area it was probably pretty recent. Not only on the bites extremely annoying, but they can also transmit diseases like malaria and West Nile. I'm sure that almost nobody has fond memories of mosquitoes. Lucky, a company called Oxitec is trying to eliminate mosquitoes, and it is entirely possible that they can.

So trying to stop mosquitoes is nothing new. There are repellants of all kind, and different tricks you use to prevent being bit. None of them really work. However, this company is doing something different by trying to reduce the population of mosquitoes, specifically Aedes aegypti,  all together. And they are doing it using mosquitoes.

Now, time for some fun science. The first thing the company does is insert a gene (there are multiple ways to do this so the exact method Oxitec does it is not clear) into male mosquitoes. Males are important because males do not bite, and so they cannot pass on any disease they could pick up. The gene produces a protein, that essentially overloads the males protein machinery, so they cannot express other important genes and die. So you might wonder why this does not kill the males? Well, the simple idea is that the gene can be switched off through giving the insects tetracycline. No expression, no protein, no dead mosquitoes. So, as long as the males are getting the antibiotic they can live their lives and reproduce, and create other mosquitoes that are have this gene.

The antibiotic is the key to the whole system, because as soon as the mosquitoes run out of antibiotic in their system the gene is expressed and they will eventually die. So, when the male mosquitoes are released into the wild, their clock is ticking. This probably gives them just enough time to release their sperm to the females before they die. So now, there are a bunch of fertilized mosquitoes eggs that will produce mosquitoes that contain this lethal gene. However, remember they do not have access to antibiotics so they will shortly die after they are born. They do not reach adulthood, and so cannot reproduce to create the next generation of mosquitoes. The result of this is a gradual decrease in the overall population.

Now, you might be wondering why females would mate with these self destructing males? Well, the answer is simple. Numbers. The range of a mosquitoes is not that big, allow Oxitec to map where they are most likely to find mosquitoes. Then by releasing enough of these "sterile" (sterile in the term that the child don't grow up and reproduce) males, they can increase the likelihood that a female will mate with one of these males. If this is done enough then overtime, the chance of mating with a sterile male increases because there is a higher and higher percentage of these males compared to normal males.

There have tests of these mosquitoes in areas in Brazil, Panama, and the Cayman Islands and they have resulted in more than 90% reduction in the wild population. These trials and so they is no way of knowing if the result can be expected of bigger areas. There are also other companies also working to genetically modify mosquitoes to wipe out populations through sterile males, Florida is currently doing a test of 20,000 mosquitoes from MosquitoMate,  and only time will tell which method works the best.

More information, including a more technically overview can be found on the Oxitec website.