Mutant bugs released to fight disease

Aedes aegypti: The female mosquito bites for blood, which she needs to mature her eggs. © Getty

Is it wrong to release modified mosquitoes into the wild? Supporters say genetically altered insects could eradicate deadly diseases, but opponents are warning of dangerous consequences.

Tropical diseases carried by mosquitoes kill a million people every year. So, it may seem strange that a laboratory wants to release 750 million of these insects into the skies of Florida, in the United States. But these are no ordinary bugs. They have been genetically programmed to destroy their own species.

This is the latest move in the fight against mosquito-borne diseases like malaria, dengue, and yellow fever. Half the world lives with the risk of infection and billions of dollars are spent every year on new drugs, pesticides, and public health measures. But the drugs are losing their potency and the mosquitoes are growing resistant to the pesticides.

Synthetic biology may offer the knock-out blow. This branch of genetic engineering allows scientists to edit the mosquito’s DNA and introduce a “self-limiting” gene. This artificial DNA sequence kills the biting females whilst leaving the modified males to spread the auto-destruct gene through the wild population.

Authorities have approved the scheme in Florida but environmental groups are furious, calling it a “Jurassic Park experiment” that will unleash a “mutant bug” into the ecosystem. Many argue that the modified mosquito may have unforeseen consequences, and an online petition against the plan already has 240,000 signatures.

Genetic modification is not new. Humans have selectively bred animals for their own advantage for thousands of years, creating friendlier pets and fatter farm animals. However, recent advances in science allow bioengineers to make precise changes to an animal’s DNA.

This gene-editing has created some curious new beasts: goats that make spider silk in their milk; cats that glow in the dark; fast-growing salmon, and pigs that can digest pollutants. Critics call them Frankenstein monsters and want them banned. But supporters believe they will make the world a better place.

But are GM mosquitoes safe? Many are concerned that releasing them into the wild will open a Pandora’s box, unleashing forces that cannot be controlled. An earlier trial in Brazil raised fears that a hybrid mosquito had been created that could survive the “lethal gene”.

Others are concerned that eliminating one species will alter the food chain, affecting those animals that eat insects.

To protect against this scenario, bioengineers have built kill switches into some of their creations. This mosquito contains a fluorescent gene, making it easier to identify.

So, is it wrong to release genetically modified mosquitoes into the wild?

Playing god

Yes, this is a dangerous experiment with too many unforeseen consequences. Nature is a complex, interconnected system where small changes can have major negative effects. In the laboratory, GM animals can be controlled and contained. But, in the wild, they will be beyond our control. And by the time we realise we have created a monster, the damage will be irreversible.

No, people’s fears are based on science fiction and disaster movies not hard evidence. In reality, scientists are conducting a controlled experiment on an insect we have already failed to eradicate by pesticides and public health measures. There is no evidence it will harm other species – but it will save thousands of lives lost every year to dengue and yellow fever.

You Decide

  1. Do we have the right to eradicate a species?
  2. Do the benefits of genetically modified animals outweigh the risks?


  1. Design your own genetically modified super-insect and draw a diagram to explain how it will improve the world.
  2. Write your own modern-day Frankenstein story in which a genetically modified animal is released into the wild, with disastrous consequences.

Some People Say...

“Mosquitoes are the greatest mass murderers on planet Earth.”

Katherine Applegate, American science-fiction writer

What do you think?

Q & A

What do we know?
It is generally agreed that the GM debate taps into long-held fears about the dangers of new technology interfering with the natural order of things. Mary Shelley’s Frankenstein drew on these anxieties, which go back to Prometheus, the Greek hero who was punished for stealing fire from the gods.
What do we not know?
One main area of debate is around the issue of playing God with nature. Religious traditions call this our role as custodian of the Earth. According to these values, we have a moral duty to respect and conserve our environment. Some argue that modifying genes to eradicate a species goes against this duty. But others ask where we should draw the line. Are pesticides and drugs also a form of playing God? And does our responsibility to protect human life come above preserving the natural world?

Word Watch

Genetically programmed
The modified variant of the Aedes aegypti mosquito was designed by the biotech company Oxitec and is known as OX5034, or the “Friendly Mosquito”.
There is no vaccine for dengue fever, which is on the rise across much of the world, driven by climate change and urban poverty. It is also known as “breakbone fever” for the acute muscle pain it causes.
Synthetic biology
In 1974, scientists inserted foreign DNA into a mouse, making the first GM animal. But only in the last decade has technology advanced sufficiently to use man-made DNA to make new synthetic organisms.
Jurassic Park
In the 1993 Steven Spielberg blockbuster, every precaution is taken to prevent a park of genetically reanimated dinosaurs from running amok. But in the words of one character, “life will find a way” – and events spiral disastrously out of control.
Friendlier pets
Humans domesticated dogs from a wolf-like ancestor about 10,000 years ago. With no knowledge of genetics, early humans selected friendly and obedient genes and eliminated aggressive behaviour.
In the 1818 novel by Mary Shelley, Frankenstein is the creator, not the monster. But the story of humans “playing God” by creating life has fed into the debate around GM, from Frankenstein foods to “frankenbugs”.
Pandora’s box
An action with unforeseen and terrible consequences is often described as opening Pandora’s box. In Greek mythology, Pandora, the first woman in the world, opened a container, unwittingly releasing evil, sickness, and death into the world. All that was left in the box was hope.
Kill switches
Some are dependent on nutrients not created in nature, whilst others contain a so-called “Deadman” gene, which causes the organism to self-destruct when it detects a change in its environment.
Invasive species
Aedes aegypti (yellow fever mosquito) originated in Africa, but has spread across much of the world. Because it is a recent arrival to ecosystems, it has not co-evolved with its environment and is not considered essential for the survival of other organisms.

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