Multistage spatial model for informing release of Wolbachia -infected mosquitoes as disease control

Abstract Wolbachia is a naturally occurring bacterium that can infect Aedes mosquitoes and reduce the transmission of diseases such as dengue fever, Zika and chikungunya. Field trials worldwide have explored its potential for epidemic control. We introduce a partial differential equation model to simulate the spatial spread of Wolbachia infection in mosquito populations. The model incorporates detailed mosquito life stages, intricate Wolbachia maternal transmission and two-dimensional mosquito dispersion. Building on prior studies showing a threshold of infected mosquitoes is required for persistence, we identify a spatial threshold, termed the ‘critical bubble’, for achieving self-sustaining Wolbachia infection. When releasing beyond this threshold, the model predicts a spatial wave of Wolbachia infection. We quantify how the threshold and infection wave velocity depend on the diffusion process and ecological parameters and examine different intervention scenarios to inform efficient Wolbachia release strategies. Our results suggest that: (i) pre-release mitigations targeting adult mosquitoes more effectively reduce the threshold than targeting aquatic stages; (ii) releases in the dry regions lower the threshold, but the infection wave propagation may slow down or stall at the dry–wet interfaces due to the heterogeneity in carrying capacities; and (iii) initiating releases just before the wet season reduces the release threshold.