Global asymptotic stability of 3-species Lotka-Volterra models with diffusion and time delays

This paper is concerned with three 3-species time-delayed Lotka-Volterra reaction-diffusion models with homogeneous Neumann boundary condition. Some simple conditions are obtained for the global asymptotic stability of the nonnegative semitrivial constant steady-state solutions. These conditions are explicit and easily verifiable, and they involve only the reaction rate constants and are independent of the diffusion and time delays. The result of global asymptotic stability not only implies the nonexistence of positive steady-state solution but also gives some extinction results of the models in the ecological sense. The instability of some nonnegative semitrivial constant steady-state solutions is also shown. The conclusions for the reaction-diffusion systems are directly applicable to the corresponding ordinary differential systems.