Production and shipment of Wolbachia-infected eggs allow controlling Aedes albopictus through the Incompatible Insect Technique on a remote island

Climate and land-use changes are accelerating the spread of the mosquito Aedes albopictus , a major arbovirus vector, leading to the emergence and autochthonous transmission of Dengue or Chikungunya viruses in temperate regions such as Italy and France. This situation is stimulating the development of innovative vector control strategies allowing to overcome the rapid selection of insecticide resistance. The Incompatible Insect Technique (IIT) allows suppressing mosquito populations through inundative releases of artificially Wolbachia infected males that sterilize local females through Cytoplasmic Incompatibility (CI). We carried out a six-month IIT suppression trial on a remote island located in the Western Indian Ocean. We used a recently constructed and optimized Aedes albopictus transinfected line sheltering a single Wolbachia infection and inducing bi-directional CI. This feature ensures that released males sterilize local females, while infected females resulting from accidental releases are also sterilized by wild-type males, thereby preventing population replacement, a key limitation of conventional IIT. The trial was conducted in operational conditions: mosquito populations were monitored during suppression and the number of released males was adjusted based on wild population density. Importantly, eggs were produced in a central insectary located over 1,000 km from the release area, transported via commercial flights to a satellite insectary for male production, and finally shipped by boat to the release site. Our results demonstrated that (i) over 95% suppression can be achieved within a few weeks of treatment, (ii) as expected the use of a mono-infected line prevented population replacement, (iii) large-scale shipment of eggs under operational conditions is both feasible and effective, supporting the scalability and industrial deployment of this environmental-friendly vector control strategy.