Edited by Eleonora Maria Vladimirou
In recent years, the growing population of tiger mosquitoes in Europe has become a serious public health issue, as the species can carry and transmit dangerous diseases. In response, France is pursuing an innovative control strategy that does not rely on chemical insecticides. Instead, it uses biological control by releasing sterile male mosquitoes. While the method has produced highly encouraging results, its high cost and regulatory challenges remain significant obstacles to widespread use.
In Montpellier, in southern France, a specialized facility breeds millions of mosquitoes every week.
The goal is not to increase the mosquito population, but to gradually reduce one of the most persistent and dangerous mosquito species to spread across Europe. French startup Terratis has developed a pioneering method in which large numbers of male tiger mosquitoes (Aedes albopictus) are bred and then exposed to X-rays to make them sterile.
Once the sterilization process is complete, the male mosquitoes are released into populated areas. There, they mate naturally with female mosquitoes but cannot produce viable offspring. As company co-founder Clélia Oliva explains, the females lay eggs, but the eggs do not hatch, breaking the species' reproductive cycle.
The idea behind the method is relatively simple but highly effective. The more sterile males released into an area, the lower the chances that wild mosquito populations will reproduce successfully. Over time, the overall mosquito population is significantly reduced without the use of chemicals that could affect the environment or other organisms.
Known as the “Sterile Insect Technique” (SIT), this approach is not a new scientific discovery. It has been used for decades in agriculture to control various harmful insects and pests that cause significant damage to crops. In recent years, however, scientists have adapted the technique to control insects that transmit diseases to humans, including the tiger mosquito.
The tiger mosquito is considered particularly dangerous because it can transmit serious viral diseases such as dengue fever, Zika virus and chikungunya. It has now been detected across most of France, while its continued spread is largely linked to climate change. Rising temperatures and milder winters are creating increasingly favorable conditions for the species to survive and establish itself in new parts of Europe, creating serious challenges for health authorities.
Despite the highly positive results from the first applications, putting the method into practice on a large scale remains a significant challenge. Frédéric Simard, head of the Research Institute for Development (IRD) in Montpellier and one of the people involved in creating Terratis, says the technology has proven that it can work effectively but is still in the early stages of development. He compared its current stage to “iPhone 1.0,” suggesting that there is still considerable room for development and improvement.
Terratis currently produces about 1.5 million sterile mosquitoes each week and plans to increase production to 40 million within the next two years. Growing demand from French municipalities and local authorities shows that more cities are looking for alternative, more environmentally friendly ways to control tiger mosquito populations.
However, producing, transporting and releasing such large numbers of insects comes with significant costs. One example is the Malbosc district of Montpellier, where a pilot program is underway. Around 100,000 sterile mosquitoes are released twice a week at 31 different locations throughout the area. According to local authorities, the program alone costs about €70,000, making it difficult to implement the method across entire cities without significant government financial support.
The new approach also faces regulatory challenges. In France, sterile mosquitoes do not clearly fit into any existing legal category because they are considered neither biocidal products nor genetically modified organisms. The lack of a specific regulatory framework creates uncertainty for investors and for the process of obtaining permits for future applications.
Despite these challenges, the initial results have been particularly encouraging. During a pilot program carried out in 2025 in the city of Brive-la-Gaillarde, a total of 11 million sterile mosquitoes were released. According to the company, about 50% of the eggs expected to hatch the following spring were already sterile, demonstrating the method's effectiveness in limiting reproduction of the species.
The ultimate goal of the strategy is not to completely eliminate the tiger mosquito from the ecosystem, since every organism plays a specific ecological role. Instead, the aim is to achieve a significant and long-term reduction in its population to levels that do not pose a threat to public health. As mosquito-borne diseases continue to increase in many parts of Europe, this method could eventually become an important tool for biological control, combining innovation with the protection of the environment and human health.
With information from AFP.
