Improving Wolbachia-based control programs in urban settings: Insights from spatial modeling

Mosquito-borne diseases such as dengue remain major global public health challenges, especially in areas facing rapid climate change. Conventional mosquito control often proves ineffective or unsustainable, highlighting the need for innovative approaches. One promising strategy is releasing Aedes aegypti mosquitoes infected with Wolbachia, a bacterium that reduces mosquito-borne virus transmission. However, spatial heterogeneity across release areas complicates large-scale Wolbachia deployment, particularly in complex urban landscapes. High spatial variation and limited access to certain regions can cause establishment failures, waste resources, and disproportionately affect disadvantaged communities. To address this, we developed a partial differential equation model that simulates the spatial spread of Wolbachia in mosquito populations. The model incorporates practical pre-release measures such as insecticide spraying and repeated releases, while accounting for variation in urban landscapes that influence mosquito movement. We identified strategies for optimizing Wolbachia releases under two common constraints: limited release size and limited pre-release insecticide effectiveness. Our results show that, under a release-size constraint, Wolbachia can establish in low-dispersal areas (e.g., backyards or gated communities) even without insecticide. In contrast, in higher-dispersal areas (e.g., parks or city blocks), reducing the wild mosquito population by 35% prior to release accelerates Wolbachia establishment within nine months. When insecticide efficacy is limited to 35%, releases smaller than the constrained maximum can still achieve 90% Wolbachia infection in low-dispersal areas, but larger releases are required in high-dispersal settings. Our simulations further suggest that splitting releases into 2-5 weekly batches can outperform a single large release, even without pre-release interventions. These findings highlight the potential of tailoring pre-release interventions and release strategies to local mosquito dispersal characteristics, offering actionable insights for cost-effective and efficient Wolbachia-based vector control programs.