October 27, 2020

Should we extinguish mosquitoes to avoid diseases in humans? | Science

Should we extinguish mosquitoes to avoid diseases in humans? | Science

The recent news about the extinction of a mosquito population in the laboratory, thanks to their genetic modification to make them sterile, it puts on the table a dilemma that many scientists have raised in recent years and that we might have to solve in a possible future: should we extinguish certain species of mosquito to prevent them from causing diseases in humans?

Medicine, ecology and ethics come into play in this complex issue that, in practice, has a vision mainlyutilitarian: Can we improve the health of humanity by extinguishing specific mosquito species without this affecting the ecosystems even more, causing natural disasters? Yes, it is a question with a totally background Spectator, in which the interests of the human being are placed before the rest of living beings. After all, medicine is specist by definition.

Historically, humanity has had few contemplations in massacring pests of rats, cockroaches, mosquitoes and other animal species to improve the health of their populations. In fact, we have practically extinguished the smallpox virus (it is still stored in high security laboratories) and we are fighting to get the same with the polio virus. The difference is that now a future possibility is reinforced to extend the extinction of species to other animals such as mosquitoes, instead of viruses. It is not that the extinction of species is precisely a novelty for the human being. His fault, Approximately 150 species die per day. With mosquitoes, however, it would be the first time that man tries to extinguish certain animal species with all his effort and extensive scientific work behind.

The tiger mosquito, which transmits the chikungunya virus.
The tiger mosquito, which transmits the chikungunya virus.

From a medical point of view, the mosquito is the number one public enemy of humanity. No animal, not even the human being (who is in second position), has killed and killed as many people as this tiny insect. Each year, mosquitoes kill 725,000 people for their role in the transmission of infectious diseases such as malaria, dengue, zika, yellow fever, West Nile virus …

Despite the above, we must bear in mind that there are about 3,500 different species and the absolute majority of them feed on plants (nectar, sap …). Only 200 species feed on human blood. In addition, the list of species that are capable of transmitting certain microorganisms that cause diseases to people is even more restricted. Therefore, it would not make sense to extinguish all mosquitoes. Only the most deadly, such as, for example, the Anopheles mosquitoes and certain Aedes mosquito species. Its eradication would mean, in principle, the salvation of thousands and thousands of human lives each year and the prevention of many diseases.

From an environmental point of view, the consequences for the extinction of certain species of mosquito are difficult to calculate, given the complex interrelationships between species in ecosystems. As Antonio Torralba, a doctor in biology and assistant professor at the University of Oviedo, explains: "We must not forget that mosquitoes are also part of trophic networks, being eaten by other insects, birds, bats … and that the decreases in Insect populations are considered as one of the causes of decreases in the populations of the animals that eat them, or that eat those that eat them. " Even so, it is true that mosquito predators have other sources of food and their disappearance may hardly affect them, but it is very difficult to predict. For example, in the Arctic, mosquitoes are an abundant source of food for migratory birds.


It could also be the case that when extinguishing certain species of mosquitoes, other insect transmitters of diseases replaced their hollow in the ecosystems, which could worsen the situation even more. In addition, male mosquitoes (only female bites) are also pollinators, so the absence of these could interfere with the reproduction of plants. As the famous concept of chaos theory warns us "Elaleteode unmariposa in Brazil can produce a tornado in Texas". Could the disappearance of certain mosquito species have serious and unexpected consequences? And, if that were the case, would we be willing to put ecosystems at risk for the noble purpose of saving human lives? The end justifies the means?

At the moment, we still do not know if this scientific approach for extinguish mosquito populations It could work in the real world. In this regard, Torralba is skeptical: "It is not feasible in nature to introduce such a high percentage of mutated individuals, there are no reasons that explain the evolutionary advantages so that a deleterious recessive mutation extends into a natural population until it ends up being a majority".

Regardless of the results that this research or others may have to eradicate certain species of mosquitoes in the real world, the truth is that we will have to continue dealing with them for many more years. Control their populations through the treatment of stagnant water, use mosquito nets and repellents, among other measures, are things that we will have to continue doing. Torralba clarifies, in that sense "undoubtedly, get effective vaccines against parasites that transmit insects would be environmentally safer and would not represent trying to extinguish species." For the moment, the deadliest animal for the human being will continue causing deaths and suffering, alien to this debate.


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