Environment: Asian tiger mosquito, ENEA's strain scales up across Europe

Over 1.5 million male Asian tiger mosquitoes (Aedes albopictus) were released this summer in Barcelona, originating from the strain developed by ENEA. This strain harbors a very common and harmless bacterium, Wolbachia, distinct from that found in wild females. This naturally produces "incompatible" males capable of sterilizing the females they mate with. It marks the first large-scale urban application in Europe of this biological control strategy, developed by ENEA and executed by Debug (Google) and Rentokil, in collaboration with the Public Health Agency of Barcelona (Agència de Salut Pública de Barcelona).

This initiative builds upon the results of a two-year trial conducted by ENEA and Debug from 2025 to 2026 at the Casaccia Research Centre (Rome), in collaboration with Sapienza University of Rome. Between late July and late October 2025, approximately 1.6 million males were released across the 53-hectare Casaccia Research Centre, achieving an 88% reduction in viable overwintering eggs compared to the control site.

An invasive and nuisance species for citizens and workers alike, the Asian tiger mosquito is also a vector for dengue, chikungunya, and Zika—diseases formerly associated with tropical and subtropical climates that are now spreading to Italy due to global warming, with several outbreaks reported in Tuscany, Lombardy, and Apulia in 2026, as well as across the rest of Europe with hundreds of cases over the past year.

ENEA was the first in the world to establish an Asian tiger mosquito strain in which native Wolbachia strains were replaced with a strain derived from the common house mosquito (Culex pipiens). Building on this achievement, ENEA developed a platform for the Incompatible Insect Technique (IIT), a method recommended by the World Health Organization (WHO) as one of the most effective and safe strategies to combat mosquito-borne diseases.

The mass-released males of the ENEA strain render wild female eggs infertile, progressively suppressing the population while reducing reliance on chemical insecticides. Google (Debug) mass-reared the strain, performed male selection, and managed transport from Miami, while Sapienza University validated the technology

and monitored control areas. The field trial is currently ongoing and will conclude in November, following early-season releases and increased dosage regimes.

The technique is highly species-specific: male mosquitoes do not bite and, once released, actively seek out females of their own species. Furthermore, no non-native molecules or organisms are introduced into the environment. As a result, it represents one of the most innovative strategies for sustainable mosquito management—an approach geared toward preventive healthcare, public health, and the future of climate-resilient urban environments.