Figure 2. Schematic illustration of factors influencing the spatial spread of Wolbachia in a mosquito population.

A. In the initial release area, the frequency of Wolbachia-infected mosquitoes needs to exceed the critical threshold for invasion (see Figure 1B) for invasion to occur. B. Wolbachia is more likely to establish and spread spatially if the initial release area is larger. C. More intense larval stage density-dependent competition slows initial establishment and spatial spread.