How to defeat tropical diseases? California and Florida want to release 32 million mosquitoes

Dengue, Zika, chikungunya and yellow fever are dangerous tropical diseases transmitted by Aedes aegypti mosquitoes, whose range is steadily expanding. In the southern United States, officials have decided to tackle this biting threat in a very unusual way by using mosquitoes against mosquitoes.

A paradoxical mosquito control project

An innovative project to combat the invasive Aedes aegypti mosquito is being developed by Alphabet, the holding company that is the parent of the well-known Google brand. Scientists working on the Alphabet Debug Initiative have submitted an application to the federal government seeking permission to release 32 million sterilized male mosquitoes into the natural environment in California and Florida. The program is expected to run for two years. What makes this solution so ingenious?

Male mosquitoes do not bite humans and therefore do not spread tropical diseases. Their primary purpose is to mate with females and, interestingly, sterilization does not diminish this instinct.

Female mosquitoes, the ones people rightly fear, also actively seek mates. They reproduce only once in their lifetime and die after laying their eggs. Scientists hope that after mating with sterilized males, the reproductive cycle of these blood-feeding insects will be effectively interrupted, leading to a decline in Aedes aegypti populations in California and Florida.

An idea borrowed from Australia

The American initiative has a strong chance of succeeding because it builds on experiments carried out in Queensland, Australia. In towns across the Cassowary Coast region, Aedes aegypti populations had expanded so rapidly that they became a public health threat.

In 2018, following extensive field trials and consultations with local communities, Australian researchers released 3 million male mosquitoes. These insects had been infected with Wolbachia bacteria, which impair the mosquitoes’ reproductive capacity. The results were remarkable. According to a study published in 2021, A. aegypti populations in individual towns were reduced by as much as 95 percent within 12 months.

As Nigel Beebe, a professor at the University of Queensland who led the Australian experiment, emphasizes, the ecological impacts are minimal and large-scale implementation is entirely feasible. Moreover, the effects of this “mosquito sterilization” appear to be long-lasting, extending into the following season.

Tropical diseases on the wing

Statistics clearly demonstrate why controlling invasive mosquitoes is so important. Florida records several hundred cases of dengue every year. Although most infections are associated with international travel, dozens result from local transmission by mosquitoes within the state.

According to the World Health Organization, between 100 million and as many as 400 million people contract dengue worldwide each year, while 5.6 billion people are at risk of infection. Many regions are experiencing an alarming upward trend. In Fiji, Samoa and Tonga, the number of reported cases in 2025 reached its highest level in a decade.

Unfortunately, as the climate continues to warm and heavy rainfall becomes more frequent, A. aegypti is expanding its range into temperate regions. In recent years, Europe has seen growing numbers of Aedes mosquitoes capable of transmitting not only dengue, but also West Nile fever, Zika, chikungunya and yellow fever.

Biological control of invasive mosquito species may prove to be a safe and effective tool for protecting people against tropical diseases. It is possible that Europe will soon begin drawing on the experience gained in the United States.

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main photo: Gab-Rysia/Pixabay

Sources:

N.W. Beebe et al., Releasing incompatible males drives strong suppression across populations of wild and Wolbachia-carrying Aedes aegypti in Australia, Proc. Natl. Acad. Sci. U.S.A. 118 (41) e2106828118, https://doi.org/10.1073/pnas.2106828118 (2021).

https://theconversation.com/google-wants-to-release-16-million-sterile-mozzies-our-australian-tests-offer-a-valuable-lesson-286359

https://www.flhealthcharts.gov/ChartsDashboards/rdPage.aspx?rdReport=NonVitalIndNoGrp.Dataviewer&cid=0172

https://www.who.int/news-room/events/detail/2026/06/15/default-calendar/world-dengue-day-2026