Innovative Mosquito Control: The Sterile Insect technique (SIT)

Switzerland is pioneering an eco-friendly approach to mosquito control using the Sterile Insect Technique (SIT). This method involves releasing sterile male mosquitoes to reduce the population of these nuisance insects without harming the environment. The SIT method is gaining traction globally as a lasting alternative to traditional insecticides, which can have detrimental effects on ecosystems. According to the World Health Institution, vector control remains a crucial component of preventing vector-borne diseases, and innovative approaches like SIT are essential.

Morcote Experiment: A Case Study in Ticino

In a groundbreaking experiment conducted in Morcote, Ticino, researchers released 3.45 million sterile male mosquitoes over two seasons (May to late September). The releases occurred at 75 strategically chosen points, spaced 50 to 80 meters apart, resulting in approximately 3,000 insects per hectare. Two technicians, traveling by car, completed the releases in about three hours across the 45-hectare test zone. Data indicated that 80% of the released males covered a 100-meter radius, while 18% ventured up to 200 meters.

Efficacy of Sterile Mosquito Release

Ticino stands out as the only temperate region where sterile mosquitoes were consistently deployed throughout the entire mosquito season. The mosquito populations in Morcote and a control commune (Caslano), which shared similar climatic and urban characteristics, were meticulously monitored weekly for 26 weeks using egg traps. The results were compelling: the average egg density in the test area was consistently lower than in the control area in both 2023 and 2024. the mosquito population was reduced by 54.8% during the peak mosquito activity period.

Challenges in Sterile Mosquito Transport

Eleonora Flacio, a leading researcher in the project, highlighted the notable challenges involved in transporting the sterilized males, which were produced in Italy. Maintaining a stable temperature between 8 and 12°C with 80% relative humidity during transit was crucial to keep the insects in a dormant state. The mosquitoes were shipped by mail, and delivery times frequently enough stretched to nearly 24 hours.

Suddenly, on arrival, mosquitoes were unusable because they were almost dead.
Eleonora Flacio, Researcher

The team explored various strategies to ensure the insects arrived in good condition, including testing different container types, providing extra nourishment before departure, and even having team members personally transport them by train from Bologna.

Optimizing Sterilization and Viability

The research team also discovered that the radiation used to sterilize the mosquitoes impacted their viability.

We have also observed that radiation – used to destroy the reproductive mosquito system – reduced their viability. The radiation dose was therefore calibrated to ensure that they survive and retain their capacity to mate.
Eleonora Flacio, Researcher

Careful calibration of the radiation dose was essential to ensure the mosquitoes survived and retained their ability to mate.Flacio emphasized the importance of well-maintained equipment and efficient transport for the success of the SIT program.

Future Plans: A Mosquito production Facility in Switzerland

Producing sterilized male mosquitoes on a large scale is a complex undertaking.

millions of larvae are produced and they must be synchronized, so that mosquitoes have the same age, the same physical condition, the same dose of radiation.
Eleonora Flacio, Researcher

The quantities required necessitate a dedicated facility. Flacio and her team are currently developing a bio-factory in Italian Switzerland, the precise location of which remains confidential. The facility will initially serve Italian Switzerland. The next phase involves expanding the program to a dozen municipalities in Ticino, contingent on securing additional funding and gathering scientific data on a broader scale.

SIT as a Sustainable Solution

The sterilization of males is a complementary technique to other control measures and has the benefit of being environmentally friendly.

After two-three days, sterilized males die, nothing remains in the environment.
Eleonora Flacio, Researcher

Unlike insecticides, which can harm entire ecosystems, SIT is a targeted approach.insecticides should only be used in the event of an epidemic. Flacio believes that SIT represents the future of mosquito control, not only for switzerland but also for other regions worldwide.