A rapidly escalating threat in Europe’s cities.
The spread of the Asian tiger mosquito (Aedes albopictus) across Europe is accelerating. Climate change has extended breeding seasons and brought milder winters, allowing this invasive species to survive and reproduce in regions that were previously unsuitable.
In 2013, the Asian tiger mosquito was established in 8 EU/EEA countries. ECDC’s latest distribution map, published in June 2026, records it as established in 16, across 384 regions. As populations become established, outbreaks of dengue and chikungunya are no longer isolated events but an emerging and persistent public health threat. West Nile virus is carried by a different species that breeds in the same catch basins — see Culex pipiens in the same urban infrastructure below.
Each year of delayed action strengthens the mosquito’s foothold, making future control more difficult, more expensive, and less effective.
Once established, the Asian tiger mosquito exploits urban infrastructure to sustain and expand its populations. Catch basins and underground water systems provide ideal, hidden breeding sites: stagnant water, stable temperatures, and protection from weather and predators.
These concealed environments allow mosquito populations to grow out of sight, directly beneath cities, increasing the risk of local disease transmission in residential areas, schools, and public spaces. This makes the Asian tiger mosquito exceptionally difficult to control with traditional, reactive methods.
The Asian tiger mosquito is not the only species exploiting urban catch basins. Culex pipiens, the principal vector of West Nile virus, breeds in the same stagnant, sheltered water — and field studies consistently find it outnumbering Aedes albopictus there.
Basel, Switzerland
A randomised trial across 180 road drains caught more than nine Culex for every tiger mosquito.
Orange County, California
Catch basins held 22% of all larval habitat for Culex quinquefasciatus, a close relative, and 97% of catch basins sampled were positive.
The consequences are not confined to Europe. West Nile virus is already the leading cause of mosquito-borne disease in the continental United States, and European transmission has spread across a growing number of countries each season. Left unaddressed, the second resident of the drain is a growing public-health threat.
Sources: Kirrmann et al., Parasites & Vectors 2025 (Basel catch basin trial); Wang et al., Scientific Reports 2021 (southern California storm drains); U.S. CDC
The current market landscape
Bacillus thuringiensis subsp. israelensis (Bti) targets mosquito larvae through bacterial proteins ingested in treated water. It is an established method for mosquito control. Effective treatment requires coverage of breeding sites, monitoring, and repeat applications depending on the formulation and local conditions. It does not directly control adult mosquitoes.
Pesticides, such as chemical insecticides, target mosquito larvae in breeding sites or adult mosquitoes through spraying. They can provide effective control, especially during disease outbreaks, but require appropriate timing, application, and monitoring. Repeated use can promote insecticide resistance, while potential effects on non-target organisms vary depending on the product and application method.
Silicone-based products form a thin film on standing water, preventing mosquito larvae and pupae from using the surface to breathe or emerge as adults. They act as a physical barrier rather than through insecticidal toxicity. Effective control depends on maintaining surface coverage, with inspection and reapplication according to product instructions and local conditions.
Sterile Insect Technique uses repeated releases of male mosquitoes sterilized by irradiation. When they mate with wild females, no viable offspring are produced, helping to reduce the target population over time. The method is species-specific and requires specialized production, reliable sex separation, repeated releases, and monitoring. It does not remove breeding sites.
Mosquitoes carrying Wolbachia bacteria are released either to suppress reproduction through incompatible matings or to establish populations less able to transmit certain viruses. Suppression requires repeated male releases, while population replacement may become self-sustaining. Both approaches require specialized breeding, coordinated implementation, and monitoring. Suitability depends on the mosquito species and local conditions.
With the exception of Wolbachia population replacement, which can become self-sustaining, every method above has to be repeated for as long as protection is wanted. ZikaSeal works differently: it denies mosquitoes access to the water rather than treating it.
