GENETICALLY ENGINEERED MOSQUITOES

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Context

Preliminary results of an open-air study of genetically engineered mosquitoes in the United States have shown promising results.

Aim

The aim of the experiment by Oxitec, is to reduce the population of wild Aedes aegypti mosquitoes that is a vector for viruses such as chikungunya, dengue, zika and yellow fever.

Background

Female mosquitoes are the ones responsible for biting humans and transferring diseases, whereas males feed only on plant nectar so do not spread any diseases.
So, the scientists engineered a gene that will kill the female offspring. The genetically modified mosquito had been developed so that females die before passing the larval stage. Let’s see how-

The Experiment

The biotech has developed OX513A, a genetically modified strain of male aegypti mosquitoes that carry a deadly gene.
When released into the environment, the engineered males should mate with wild females, and their female offspring will die before they can reproduce. Male offsprings will carry the gene and pass it on to half of their progeny. As each generation mates, more females die, and the aegypti population should dwindle.
The researchers claimed in the results that all females that inherited the lethal gene died before reaching adulthood indicating that the experiment's main goal was a success.

How GM mosquitoes are produced in Lab?

A self-limiting gene that prevents female mosquito offspring from surviving to adulthood.
A fluorescent marker gene that glows under a special red light. This allows researchers to identify GM mosquitoes in the wild.

GM mosquitoes produced in the laboratory lay eggs. These eggs carry the self-limiting and fluorescent marker genes.
GM mosquito eggs that carry the self-limiting gene are released into an area. Once they have hatched and develop through to the adult stage, they are available to mate with wild females. The genes are passed on to offspring.
The female offspring die before they become adults. The expected result is that the number of aegypti mosquitoes in the area decreases.

Effectiveness of GM mosquitoes in reducing numbers of mosquitoes

GM mosquitoes have been successfully used in parts of Brazil, the Cayman Islands, Panama, and India to control aegypti mosquitoes. Since 2019, over 1 billion mosquitoes have been released.
In Brazil, Oxitec’s mosquitoes have demonstrated to reduce the local populations by more than 90%, whereas insecticides only affect 30%.
The World Health Organization (WHO) backed the engineered mosquitoes during Zika outbreak. The company released 10,000 of them in one of the Cayman Islands, drastically reducing the local mosquito population.

How can it be significant for India?

Dengue is estimated to infect 5.8 million people in India every year, costing the country over $1B annually.
Outbreaks of chikungunya, a viral disease for which no treatment is available, have been increasingly reported in India. Both diseases are transmitted by local populations of Aedes aegypti
Thus, Oxitec is rightly conducting trials in India to reduce the population of disease-transmitting insects in India with its own genetically modified mosquitoes.
This strategy only targets a specific mosquito strain and does not produce any toxic compounds that could affect their predators. Thus, this is the most eco-friendly solution so far to control the spread of infectious diseases.

Significance

The use of GM organisms is less invasive and has proved more effective than any other solutions currently available to control the spread of infectious disease.
While its mosquitoes continue fighting disease, Oxitec is now exploring expanding its technology to flies. The Mediterranean fruit fly, Ceratitis capitata, is one of the most destructive agricultural pests, causing billions of dollars in damage and affecting over 250 types of fruits, nuts and vegetables. Oxitec has carried out trials in Greece and Morocco and is now preparing for its first open field trial.

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