Figure 4

Threshold analysis of parameter \(\sigma _{11}\) in system (2.1) with \(x(0)=0.3\), \(y(0)=0.3\), \(c_{o}(0)=0.3\), \(c_{e}(0)=0.3\), \(D=1\), \(\beta =0.1\), \(k=0.1\), \(A=1.5\), \(B=1\), \(r=0.2\), \(f=0.1\), \(g=0.5\), \(m=0.5\), \(h=0.1\), \(\mu =0.2\), \(h_{1}=0.3\), \(h_{2}=0.2\), \(\sigma _{12}=0.01\), \(\sigma _{21}=0.01\), \(\sigma _{22}=0.01\), \(l=0.25\), \(\tau =4\). (g): \(y(t)\) survival with parameter \(\sigma _{11}=0.03\); (h): \(y(t)\) extinction with parameter \(\sigma _{11}=0.4\)