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 every summer in thousands of Catalan homes: the light off, the silence of the night, and suddenly, the sharp, insistent buzzing that grazes 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 slap of a slipper, we put an end to the annoyance. Until recently, this domestic victory returned us the tranquility of a bite-free sleep. Today, however, this gesture hides a much more disturbing reality: the mosquito is no longer just an annoying neighbor, it has become the vector for diseases that just 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 only arrives by plane, but circulates among us through the tiger mosquito ("Aedes albopictus). This invasive species, recognized by its white stripes and its diurnal activity, has joined the common mosquito (Culex pipiens), the one of a lifetime, which is nocturnal and acts as the main transmitter of the Nile virus. As researcher Rachel Lowe, director of the Global Health Resilience group at the Barcelona Supercomputing Center (BSC-CNS), explains, "Barcelona is a global hub with a high risk of emergency or re-emergence of various pathogens." According to Lowe, rising temperatures and altered rainfall patterns create a "perfect cocktail" for the expansion of these vectors.
Key to biodiversity
However, science demands perspective. Faced with the temptation to exterminate the mosquito, we must remember that it is an irreplaceable part 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 support insectivorous birds, bats, and dragonflies. Furthermore, they act as silent pollinators; some plants, like the Arctic orchid, depend on them almost exclusively for survival. As Juana Díez, a researcher at Pompeu Fabra University (UPF), points out, "getting rid of" the mosquito would not only be useless but an ecological disaster, as 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 UPF researcher and co-founder of Mosquito Alert.. The real engine of the epidemic is the journey of the pathogen 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 the saucer of a pot to colonize an urban environment.
This scenario forces a shift from brute force to anticipation. Indiscriminate insecticide, which Díez calls a resounding "no-no" for its ability to destroy entire ecosystems and generate resistance, is no longer enough. The challenge for science today is hacking: biological surgery to disarm the virus without annihilating the insect, protecting our health while respecting the biodiversity that sustains us.
Reprogram the insect to disarm the virus
To understand how we can coexist with the mosquito without suffering its diseases, we need to 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 throughout their lives without killing them. While in the human body the virus acts as an aggressive invader that "exploits" cellular machinery to the point of destroying 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's as if the virus turned down the volume of its own activity," explains Díez. This phenomenon, called translation 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 doesn't want to kill the one that is feeding it".
The ultimate goal of this research, supported by the "La Caixa" Foundation, is to use this knowledge to apply biological "surgery" to the transmission cycle. The horizon is not the extermination of the mosquito – an objective that Díez dismisses because insecticide "is proven not to work" and has a very large environmental impact – but its hacking. "If we manage to alter this balance, forcing the virus to reproduce uncontrollably or, conversely, blocking its ability to persist, we could make mosquitoes stop acting as vectors," explains the researcher.
This study opens the door to the design of mosquitoes that are naturally resistant to infection by modulating their own proteins. This is a sophisticated alternative to current methods such as the use of the bacterium Wolbachia, which is not always effective depending on the climate or environment. In a context where the tiger mosquito already bites in Barcelona even in December, Díez insists that understanding these survival mechanisms has ceased to be a purely academic issue to become an essential piece in 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 public space, you just have to take a picture and send it through the app.
- 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 treatments and prevention should be focused.
- 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 works on molecular hacking, at the Doñana Biological Station (EBD-CSIC) the focus shifts to the field: wetlands and urban areas where risk materializes. Jordi Figuerola, an expert in zoonotic diseases, leads the Arbo-prevent project, an initiative – supported by the "La Caixa" Foundation – that aims to become a sort of virus "weather forecaster." The objective is ambitious: to have a surveillance system that allows threats to be predicted weeks in advance.
This prevention network is not a hypothesis but an operational reality. Through traps placed in strategic locations, 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," states Figuerola. The system has already been successfully tested: a model presented in 2025 allowed the Nile virus to be located in Almeria, an area with no previously known circulation, and it was accurate in 6 out of the 10 municipalities where a higher risk had been indicated.
However, Figuerola introduces a necessary nuance to the discourse on coexistence: "Since we have to kill mosquitoes, we must know how to kill them so as not to end up destroying all biodiversity." The key to this strategy lies in attacking during the larval stage. While the larvae are in the water, their control is simpler and more economical using biological products such as Bacillus thuringiensis, a bacterium that generates toxins that only affect mosquitoes and leave the rest of the species intact. On the contrary, if we wait for the insect to reach adulthood and fly, we must resort to adulticides, much more toxic and non-specific insecticides, which decimate 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 virus circulation is detected in an area, the information is communicated to the Ministry of Health, and from there to primary care centers, so that the medical professional knows exactly what to look for.
Finally, Figuerola recalls that the best prevention technology is a healthy nature through the lens of one health. Fostering 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 is 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 mass, rapid, and economic diagnosis in resource-limited environments. Although its most recent validation has focused on malaria, the philosophy is the same as that of UPF or Doñana: to use technological precision as a tool for "hacking of the transmission chain.
The team has designed an innovative paper-based device that only needs a drop of blood obtained from the patient's finger to function. The great advantage of this tool over conventional rapid tests is that it offers quantitative results. "This allows us to estimate the parasitic load and the severity of the disease," explains the VHIR team. This is a critical step to identify not only who is sick, but who has the potential to become a major transmitter.
- Weekly surveillance: any container that can accumulate water – such as terracotta 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.
- Indoors: don't forget the invisible critical points. If you have infrequently used drains or gullies, the experts' advice is to put 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. Breeders have even been found inside a broken dishwasher.
- Clothing and repellents: in risk areas and during peak activity hours (sunrise and sunset), the use of long sleeves and appropriate repellents is the last line 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 show no 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 the acid test. In October 2025, three researchers from the group traveled to the Nossa Senhora da Paz Hospital in Cubal, Angola, to test the prototype under real field conditions. There, far from the stability of the laboratory, they had to lyophilize the reagents to avoid relying on the cold chain. "For the first time we've taken the technology to the field, the performance has been very commendable. Now we know what we need to improve," summarizes Baldrich.
This project, called CATMAL and also supported by the "la Caixa" Foundation, does not seek only to export technology from Europe, but to establish the foundations so that it can be manufactured and used directly where needed. It is the culmination of a global strategy: if we are capable of accurately diagnosing and reprogramming the mosquito's biology, we will be able to finally sideline the indiscriminate fumigations that harm our environment. As Catalan science has shown, "hacking" the mosquito is not about eliminating it; it is about disarming the danger to protect life in all its forms.