Along with giving us annoying bug bites, in parts of the world they are the vector for the spread diseases and Illnesses like malaria, yellow fever, and zika virus to man kind. So if you were given the tools to eliminate mosquitoes from the face of the planet would you do it? The ethics of this question needs to be considered.
Right now efforts to prevent mosquito bites are using insecticides, repellent, traps, mosquito-larva- eating-fish, and bed nets etc.
The mosquito is not the directly the problem, it’s the diseases that they carry. But only a few species carry and transmit disease. Plasmodium falciparum is an example of a species of mosquito that carries the malaria parasite. There are thousands of species of mosquitoes but only a few are vector for transmission of diseases so eliminating all of them using pesticides would not be smart. Using pesticides kill the bad and good insects indiscriminately which is a major problem.
In response to this scientist make developed a ways to target the species that we want to focus on. species . One such method is CRISPER- Cas9 that disrupts the fertility of female mosquitoes. It starts in a lab where the gene is injected into the fertilized eggs. It works by inserting itself into both chromosomes of the DNA so that all gametes of the mosquito have the gene. It then it propagates through a population to wild female types by altered males. All offspring have the gene if male if altered. Altered male offspring can then go and continue spreading the gene while altered female offspring are no longer about to reproduce. this method is more successful then others because the gene it able to copy its self in to both chromosomes of a pair. Also mosquitoes can't develop a resistance like they can with pesticides.
There are ethical and other unforeseen concerns about the decision to use this technology. Some feel that it is not right to do ahead and wipe an entire species. Others don't think of the mosquito as significant enough to care about preserving it. However since mosquitoes don't travel far from where they where born researchers don't think it will have a complete annihilation affect. But it will severly decreases the regional populations when it is needed. Some people also worry about the potential for this to used as a biological weapon if it gets into the wrong hands.
Some unforeseen problems a very likely to appear. The elimination one of the species that carries may lead to the rise of another. One species West Nile Virus does poorly in the the presence of a species that carries malaria. So the West Nile virus containing mosquito may become a problem when the malaria containing population has decreased or been eliminated.
In certain area mosquitoes are also seasonal reservoirs of food for animals such as migrating birds in the arctic tundra.
The decision we face of whether or not to develop and use CRISPER-Cas9 method on mosquitoes is kind of like Dr. Sarisawa's dilemma. He had to choose whether or not to allow the use of the oxygen destroyer to be used on Godzilla. Now we have to decide whether or not to use these new methods on mosquitoes because although their bites are harmless, what can be transmitted is not. The figure below shows a comparison to the annual deaths for mosquitoes and other animals that many people fear and think of as killers.
Images and story are from and on the Mosquitoes are from the Smithsonian magazine.
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