Sterile insect technique for suppression of endemic Aedes albopictus in urban Reunion Island : a pilot trial of technical feasibility and entomological impact

Abstract

BACKGROUND : The sterile insect technique (SIT) has progressed from theory to a validated vector control strategy for Aedes-borne diseases, including dengue and chikungunya. We assessed the feasibility and effectiveness of SIT for suppressing Aedes albopictus in small-scale urban environments on Reunion Island. METHODS : From July 2021 to September 2022, over 10 million Ae. albopictus males sterilized as pupae with 40 Gy X-rays were released at a 20-hectare pilot site. Weekly releases ranged from 60,000 to 275,000 males (3000-13,750 per hectare). Outcomes were monitored using ovitrap surveillance and periodic adult sampling during a 6-month baseline and a 13-month intervention. RESULTS : Sterile-to-wild male ratios ranged from 6:1 to 18:1. Compared with the control site, the treated site showed a 33.5% reduction in egg abundance and a 61.5% reduction in egg viability (range 40.0-81.9). Reductions in egg fertility were temporally aligned with a 60.4% decline in female abundance relative to baseline. CONCLUSION : This study demonstrates that SIT was technically and logistically feasible and achieved measurable suppression of Ae. albopictus. Despite scale and operational constraints, the intervention achieved significant reductions in egg fertility and female abundance, providing strong proof of concept for SIT-based mosquito control on Reunion Island.

HIGHLIGHTS • This pilot study confirmed the SIT technical and logistical feasibility in real world conditions. • Field data confirmed sterile male releases effectively reduced of urban mosquito populations. • A marked and sustained decline was evident in egg production, fertility and adult female abundance. • Cross-stakeholder collaboration, community support and source reduction improved SIT success. • Larger-scale trials required in order to assess the long-term epidemiological impact.