Hopf Bifurcation in an S–I–P Dynamic Model with Disease in the Prey Population and Holling Type III Functional Response

Bifurkasi Hopf pada Model Dinamik S-I-P

Abstract

In this paper, a dynamic S-I-P model with disease in the prey population and Holling type III functional response with time-delay were discussed. Model analysis is carried out by determining fixed points, then analyzing the stability of the fixed points and discussing the existence of the Hopf bifurcation. Another modification given to the model is the use of time delays. Delay time is the time needed for a disease to make prey sick (incubation time). The first case is a model without time delay, it is obtained that 3 fixed points are unstable and 2 fixed points are stable. One of them is the interior fixed point tested with the Routh-Hurwitz criteria. The second case is a model with a delay time, the critical delay value is obained. Hopf bifurcation occurs when the delay time value is equal to the critical delay value and also fulfills the transversality condition. Observations on the model simulation are carried out by varying the value of the delay time. When the Hopf bifurcation occurs, the graph on the solution plane shows a constant oscillatory movement. If the value of the delay time given is less than the critical value of the delay, the system solution goes to a balanced state. Then when the delay time value is greater than the critical delay value, the system solution continues to fluctuate causing an unstable system condition.