The secret tool to make mosquitoes stop being dangerous
Science proposes a strategic change: to protect human health without destroying the biodiversity that sustains us
The scene repeats itself every summer in thousands of Catalan homes: the light off, the silence of the night and, suddenly, the high-pitched and insistent buzzing that brushes against our ear. The reaction is almost a Pavlovian reflex: we turn on the light, look for the little invader on the wall and, with a sharp blow of a slipper, we put an end to the annoyance. Until recently, this domestic victory returned to us the tranquility of a sleep without bites. Today, however, this gesture hides a much more disturbing reality: the mosquito is no longer just an annoying neighbor,it has become a vector for diseases that until four days ago we considered exotic.Catalonia has entered a new epidemiological era. The dengue outbreak in Vila-seca in the summer of 2024, with eight autochthonous cases, was the definitive alarm signal: the virus no longer just arrives by plane, but circulates among us through the tiger mosquito (Aedes albopictus). This invasive species, recognized by its white stripes and diurnal activity, has joined the common mosquito (Culex pipiens), the traditional one, which is nocturnal and acts as the main transmitter of the West Nile virus. As explained by researcher Rachel Lowe, director of the Global Health Resilience group at the Barcelona Supercomputing Center (BSC-CNS), "Barcelona is a global hub with a high risk of emergence or re-emergence of various pathogens". According to Lowe, rising temperatures and changing rainfall patterns create a "perfect cocktail" for the expansion of these vectors.
Key for biodiversity
However, science demands perspective. Faced with the temptation to exterminate the mosquito, one must remember that it is an irreplaceable piece of the vital machinery. Mosquitoes are the supermarket of biodiversity: their larvae filter organic matter and are essential food for fish and amphibians, and the adults sustain insectivorous birds, bats, and dragonflies. Furthermore, they act as silent pollinators; some plants, such as the Arctic orchid, depend on them almost exclusively to survive. As the researcher at Pompeu Fabra University (UPF) Juana Díez points out, “getting rid of” the mosquito would not only be useless, but an ecological disaster, since its niche could be occupied by even more dangerous species.
The key to the current situation is the combination of climate crisis and globalization. The interconnected world has created highways for viruses. Although a mosquito's flight capacity is minimal, human mobility has dynamited borders. "Mosquitoes have a limited flight radius, but humans cross continents," states John Palmer, a researcher at UPF and co-founder of Mosquito Alert. The real engine of the epidemic is the pathogen's journey within us in a world where Barcelona acts as an international hub. Furthermore, global trade facilitates passive transport: the tiger mosquito arrived hidden in containers and used tires, which act as perfect "micro-niches" for its resistant eggs. Unlike other species, the tiger does not need large wetlands; it has enough with the water accumulated in a small vase or a plant pot saucer to colonize an urban environment.
This landscape forces us to move from brute force to anticipation. Indiscriminate insecticide is no longer enough, which Díez describes as a resounding "no-no" due to its capacity to destroy entire ecosystems and generate resistance. The challenge for science today is hacking: a biological surgery to disarm the virus without annihilating the insect, protecting our health while respecting the biodiversity that sustains us.
Reprogramming the insect to disarm the virus
To understand how we can coexist with mosquitoes without suffering from their diseases, we must look inside the cells. At UPF, the Molecular Virology Group, led by Dr. Juana Díez, has deciphered one of nature's best-kept secrets: why lethal viruses like chikungunya or dengue persist in mosquitoes for their entire lives without killing them. While in the human body the virus acts as an aggressive invader that "exploits" the cellular machinery until it destroys the cell, in the mosquito the relationship is much more discreet and strategic.
Díez defines this relationship as a "pact of silence." According to her team's study, published this spring in the journal PLOS Biology, the virus adopts a moderate approach in the insect: although its genetic material accumulates, the production of viral proteins is limited. "It is as if the virus turned down the volume of its own activity," explains Díez. This phenomenon, called translational repression, allows the virus to reproduce enough to ensure transmission in the next bite without overloading or damaging the host organism. As Díez summarizes, "the virus does not want to kill the one providing its food."
The ultimate goal of this research, which is supported by the La Caixa Foundation, is to use this knowledge to apply a biological "surgery" to the transmission cycle. The horizon is not the extermination of the mosquito—a goal that Díez dismisses because insecticide "is proven not to work" and has a very large environmental impact—but rather its hacking. "If we manage to alter this balance, by forcing the virus to reproduce uncontrollably or, conversely, by blocking its ability to persist, we could make mosquitoes stop acting as vectors," the researcher explains.
This study opens the door to the design of mosquitoes that are naturally resistant to infection through the modulation of their own proteins. It is a sophisticated alternative to current methods such as the use of the Wolbachia bacterium, which is not always effective depending on the climate or environment. In a context where the tiger mosquito is already biting in Barcelona even in December, Díez insists that understanding these survival mechanisms has ceased to be a purely academic matter and has become an essential piece for responding to a real emerging threat.
- How it works?: If you see a mosquito that looks suspicious (like the tiger mosquito or the yellow fever mosquito) or a breeding site in a public space, you just need to take a photo of it and send it through the application.
- Expert validation: A digital laboratory of entomologists from all over the world receives the images, validates them, and determines the species.
- Real impact: The data is integrated almost in real-time into the maps of public health agencies, such as Barcelona's, to decide where to focus treatments and prevention.
More than 286,000 reports: So far, this platform has received thousands of citizen reports that help researchers understand how vectors move from one continent to another.
The radar that anticipates the virus
While UPF is working on molecular hacking, at the Doñana Biological Station (EBD-CSIC) the focus shifts to the field: wetlands and urban areas where the risk materializes. Jordi Figuerola, an expert in zoonotic diseases, leads the Arbo-prevent project, an initiative –supported by the La Caixa Foundation– that aspires to become a kind of "weatherman or weatherwoman" for viruses. The goal is ambitious: to have a surveillance system that allows for predicting threats weeks in advance.
This prevention network is not a hypothesis but an operational reality. Using traps located at strategic points, Figuerola's team carries out weekly captures to identify mosquito species and analyze them by real-time PCR. "We are capable of detecting the virus in the mosquito a month before cases begin to be diagnosed in humans," Figuerola states. The system has already been successfully tested: a model presented in 2025 allowed the location of the Nile virus in Almeria, an area with no known previous circulation, and was correct in 6 out of the 10 municipalities where a higher risk had been indicated.
However, Figuerola introduces a necessary nuance in the discourse of coexistence: "Since it is necessary to kill mosquitoes, one must know how to kill them so as not to end up destroying all biodiversity." The key to this strategy consists of attacking in the larval phase. While the larvae are in the water, their control is simpler and cheaper using biological products such as Bacillus thuringiensis, a bacterium that generates toxins that only affect mosquitoes and leave the rest of the species intact. Conversely, if one waits for the insect to reach adulthood and fly, it is necessary to resort to adulticide insecticides, which are much more toxic and nonspecific, and which destroy the entire ecological niche.
This fieldwork has a direct impact on the healthcare system. The Nile virus is not easy to diagnose; the symptoms can be confused with other pathologies, especially in the elderly. The Doñana sentinel network acts as a radar for doctors. When the circulation of the virus is detected in an area, the information is communicated to the Ministry of Health, and from there to primary care centers, so that medical professionals know exactly what to look for.
Finally, Figuerola reminds us that the best prevention technology is a healthy nature under the prism of one health (one health). Favoring the presence of natural predators such as bats, swallows, dragonflies, and aquatic beetles is the most intelligent and sustainable form of control. "The more natural predators we have, the less we will have to worry about mosquitoes," he concludes. It is risk management through biodiversity: protecting the ecosystem to, ultimately, protect ourselves.
The scalpel to cut the transmission
The last piece of this puzzle can be found at the Vall d'Hebron Research Institute (VHIR). The Diagnostic Nanotools (DINA) group, led by Dr. Eva Baldrich, has been working since 2018 on the development of a technology that allows for massive, rapid, and affordable diagnosis in resource-limited settings. Although its most recent validation has focused on malaria, the philosophy is the same as that of the UPF or Doñana: to use technological precision as a tool for hacking the transmission chain.
The team has designed an innovative, paper-based device that only requires a drop of blood obtained from the patient's finger to function. The great advantage of this tool compared to conventional rapid tests is that it offers quantitative results. "This allows for estimating the parasite load and the severity of the disease," explains the VHIR team. This is a critical step in identifying not only who is sick, but also who has the potential to become a major transmitter.
Weekly surveillance: any container that can accumulate water—such as flowerpot saucers, buckets, and garden toys—must be emptied at least once a week to break the breeding cycle.
- The danger of tires: They are ideal micro-habitats for the tiger mosquito. Their eggs can survive for months in dry conditions and reactivate immediately when they receive water again.
- Inside the house: do not forget the invisible critical points. If you have drains or gullies that are rarely used, the experts' advice is to place large stones in them, drain them, or apply a little bleach to prevent them from becoming mosquito factories.
- Air conditioning: if you collect condensation water in bottles or containers, remember to empty them frequently. Breeding sites have even been found inside broken dishwashers.
Clothing and repellents: in high-risk areas and during peak activity hours (sunrise and sunset), wearing long sleeves and using appropriate repellents is the final barrier of personal defense.
This diagnosis is vital for locating asymptomatic patients. In diseases like malaria –there are still more than 200 million cases and it causes half a million deaths annually– or dengue, people who do not show symptoms act as silent reservoirs: the mosquito bites them, picks up the pathogen, and transmits it to the next healthy person. Cutting this chain of contagion through early detection is, in essence, a surgical intervention on the social body.
The technology has already passed its trial by fire. In October 2025, three researchers from the group traveled to the Nossa Senhora da Paz Hospital in Cubal, Angola, to test the prototype in real field conditions. There, far from the stability of the laboratory, they had to lyophilize the reagents to avoid depending on the cold chain. "For being the first time we have taken the technology to the field, the performance has been very worthy. Now we know what we need to improve," summarizes Baldrich.
This project, called CATMAL and which also has the support of the La Caixa Foundation, does not just seek to export technology from Europe, but to establish the foundations so that it can be manufactured and used directly wherever it is needed. It is the culmination of a global strategy: if we are capable of diagnosing with precision and reprogramming the biology of the mosquito, we will finally be able to push aside the indiscriminate fumigations that damage our environment. As Catalan science has demonstrated, hacking the mosquito is not about eliminating it; it is about disarming the danger to protect life in all its forms.