Study case of direct sensitivity analysis applied to host pathogen cycles in self-regulated forest insect systems

In this paper, we present a case study on the calculation of variation of state variables from the nominal trajectory to variations in initial conditions and parameters variation applied on host-pathogen cycles in self-regulated forest insect system. In this study we used for numerical calculation and computer simulation, direct sensitivity analysis. Mathematical model considered is the model's G Anderson and May (1981). For this system we calculated sensitivity functions with respect to initial conditions in relation to the parameters. With sensitivity functions with respect to initial conditions in relation to system parameters can be done various scenarios. The advantage of this method is that enables us to determine the contribution of each state perturbations to the trajectory deviation.