Periodic Solutions for a Predator-Prey Model with Periodic Harvesting Rate

In the paper, we study the existence of periodic solutions in an invariant manifold for a predator-prey model with periodic harvesting rate. Without harvesting, the predator-prey system has a positive equilibrium of center type, which undergoes Hopf bifurcation. Under the periodic harvesting, we first reduce this predator-prey system to a complex normal form. Then, we define the Poincare mapping of this system by using the polar coordinates, and prove that there exists an integral manifold and periodic solution with the period of the harvesting rate. An example is provided to illustrate the result.