Summary
Rentokil Initial and Debug say more than 1.5 million male Asian tiger mosquitoes carrying a Wolbachia strain were released in Barcelona as part of a mosquito-suppression pilot. The companies cite a separate Rome trial, where fertile overwintering egg production fell by up to 88% in the 2025 season compared with control areas.
Rentokil Initial and Debug say they released more than 1.5 million male Asian tiger mosquitoes carrying a Wolbachia strain in selected urban green areas of Barcelona. The pilot, conducted with the Public Health Agency of Barcelona (ASPB), uses incompatible insect technique (IIT) to suppress local mosquito populations. Rentokil describes it as the first at-scale urban deployment of this approach in Europe.
How the incompatible-insect method works
The released males carry an ENEA-developed mosquito line known as ARwP. Its Wolbachia bacteria differ from those in wild Asian tiger mosquitoes. When these males mate with wild females, the resulting eggs do not hatch, reducing the number of mosquitoes in later generations. Male mosquitoes do not bite people, according to the announcement.
Debug rears the mosquitoes and uses automated production and AI-driven sex sorting to prepare male-only shipments. ASPB and Rentokil share responsibility for import logistics, field releases and monitoring through a network of traps. The Barcelona programme involved weekly releases of about 80,000 males during the summer.
This method targets mosquito reproduction rather than killing adult mosquitoes directly. The partners say it is intended to work alongside existing pest-management measures as part of a broader approach to mosquito control.
Rome results provide the reported efficacy benchmark
The Barcelona work builds on a two-year Debug–ENEA field trial at the ENEA Casaccia Research Centre in Rome, conducted over a suburban area of 53 hectares. The 2025 season showed a reduction of up to 88% in the production of fertile overwintering eggs compared with control areas, according to Rentokil Initial. That result concerns egg production, not a measured reduction in mosquito-borne disease.
The Rome figure is the reported efficacy result; the announcement describes Barcelona as an operational pilot with trap-based surveillance but gives no measured outcome for that site. The companies say the partnership is designed to adapt the approach for other European locations, with local public-health authorities involved in authorisations and implementation.