The vision sounds tempting: a world without malaria, without dengue fever, and without the torment of mosquito bites at night. Around 250 million people contract malaria every year, and more than 600,000 die from it – most of them children under the age of five. Against this backdrop, eradicating the Anopheles mosquito, which transmits the disease, can almost seem like a moral obligation. There is also a strong desire to move away entirely from DDT, which the WHO still recommends in places where no alternatives are available. Modern research now makes possible a far more effective intervention, as highlighted in an article by the NZZ. The magic word is gene drive.

Technologically, gene drives are based on the CRISPR/Cas gene-editing system. In agricultural plant breeding, genome editing using CRISPR/Cas has already become widespread in many countries in order to make crops more resistant to diseases or drought. Governments around the world generally regard the technology as safe. It is also considered more precise than conventional breeding methods, which often rely on untargeted mutagenesis – in other words, random genetic changes induced by radiation or chemicals. CRISPR/Cas enables scientists to alter desired traits in a targeted and controlled way and helps where traditional breeding methods reach their limits. For this reason, Switzerland has repeatedly approved field trials involving these beneficial genetic scissors.

Gene drive, however, uses CRISPR/Cas in a far more far-reaching way. The gene-editing mechanism is inserted into the organism’s DNA in such a way that it copies itself during reproduction and actively rewrites the genetic information of the mating partner. This turns the modification into a biological self-propagating system: the trait is passed on to almost 100 percent of offspring, regardless of which individuals the organism mates with.

While genome editing in plant breeding remains a controlled tool for targeted improvement, the long-term consequences of gene drives for entire wild populations and ecosystems are extremely difficult to predict. This prospect raises profound ecological concerns. Mosquitoes are far more than annoying bloodsuckers; they are an essential part of natural ecosystems. Their larvae act as a kind of environmental cleanup crew in aquatic systems, filtering organic material and helping to stabilize water quality. They also serve as an important food source for fish, birds, and bats. The complete disappearance of certain mosquito species could leave gaps in the food chain whose consequences we can barely foresee today.

Gene Drive “Light”

Beyond ecology, the ethical dimension lies at the center of the debate. Should humans have the right to decide that an entire species ought to disappear from the planet? Supporters point to the millions of human lives that could be saved and to the enormous economic relief such measures could bring to entire continents. Critics, on the other hand, warn of the irreversible loss of biodiversity and the risk that the ecological niche left behind could be filled by even more dangerous pathogens.

A less radical solution might involve targeting not the mosquito itself, but only its role as a disease vector, as the NZZ notes. Researchers are working on gene drives that strengthen the insects’ immune systems so that malaria parasites can no longer survive inside them. In this scenario, the mosquito would remain part of the ecosystem and continue to perform its ecological functions. It would still bite humans, but it would no longer be a deadly carrier of disease.

The canton of Ticino has also chosen a somewhat less invasive strategy to slow the spread of the Asian tiger mosquito, which can transmit dengue fever: releasing sterile male mosquitoes.

In any case, keeping an open mind about the opportunities these technologies may offer – and fostering a debate that considers not only the risks of using them, but also the risks of not using them – can be valuable, as emphasized in a fact sheet published by SCNAT Wissen.