Suppression of Aedes aegypti by the sterile insect technique on Captiva Island, Florida, USA from 2020 to 2022

Aedes aegypti, an aggressive nuisance biter and the primary vector for numerous arboviruses, such as chikungunya, dengue, and Zika, presents significant control challenges due to its ability to thrive in urban environments, escapes insecticide treatment by using cryptic resting and oviposition sites, and development of resistance to chemical mosquito control products being used routinely. From 2020 to 2022, the Lee County Mosquito Control District (LCMCD) employed the Sterile Insect Technique (SIT) to test a new approach in its integrated mosquito management toolbox, targeting the population suppression of Ae. aegypti on Captiva Island, Florida. Over 24.1 million sterile males were released across three phases, covering up to 142 hectares. The study demonstrated a population reduction of up to 79% in wild adults and a 59% decline in egg densities in the primary intervention area. While population control was successful, an influx of wild females from untreated zones posed ongoing challenges to complete suppression in areas close to non-intervention areas. This supported a need for an area-wide integrated pest management (AW-IPM) approach. These results underscore SIT’s potential as a critical tool in integrated mosquito management strategies and emphasize practical application.Author summary: Aedes aegypti is a major nuisance mosquito in many warm places across the world. This species is particularly significant for vector control programs because it has high capacity to transmit viruses that can cause human disease including dengue virus, Zika virus, and chikungunya virus. Traditional chemical control treatments are not always effective for Ae. aegypti, because larvae breed in dispersed sites, their adults rest in cryptic locations, and insecticide resistance has evolved in some populations. Thus, additional control tools are needed for this species. Here we show that the sterile insect technique (SIT), a long-standing tool in agricultural pest management, can be effectively used to suppress a nuisance population of Ae. aegypti on Captiva Island in Florida, USA. Specifically, we released just over 24 million sterile, lab-reared males between June 2020 to September 2022 and show that the number of wild females was substantially reduced in our intervention site compared to both the same site before intervention and non-intervention sites. Our work demonstrates that SIT should be considered for use as part of the toolbox for the integrative management of mosquito pests.