Fig 6. The trajectory of the system Eq (7) with initial condition (0,0,0,0,10000,1) and parameters L = 1500, w = 21000, v = 10000, α ₄ = 0, α ₃ = 0.0005, α ₂ = 1, α ₁ = 0.001, φ ₁ = 1/3, φ ₂ = 1, σ = 0.001, β ₁ = 1/5, β ₂ = 1/13, and μ = 1/30.

This figure shows that the colony dies out if one of the adult bees is carrying enough spores to start infection.