A 3-year entomological cluster randomised controlled trial to assess the efficacy of mass-trapping for Aedes albopictus control in France: The vectrap project

The Asian tiger mosquito, Aedes albopictus, is a significant public health threat due to its ability to spread diseases such as dengue and chikungunya. Traditional insecticide-based control methods are increasingly ineffective due to mosquito resistance and environmental concerns. This has driven interest in alternative strategies like mass trapping, although its effectiveness in reducing Ae. albopictus populations at the community level remains unclear. This study aimed to evaluate a mass trapping intervention over three years in six peri‑urban communities in France, using a Cluster Randomized Controlled Trial (CRCT) design. The intervention combined passive oviposition and host-seeking traps with source reduction and larviciding in the first two years. In the third year, control shifted to a community-based approach, with residents maintaining traps and managing breeding sites. Mass trapping reduced mosquito abundance by 36-64 % in some communities, though efficacy varied due to local conditions, trap density, and implementation differences. The highest reductions occurred with high trap density and house coverage. The third year revealed challenges in sustaining community participation, impacting overall effectiveness. This study provides valuable insights into the practical application of mass trapping, emphasizing the need for tailored approaches adapted to local contexts.