A note on the existence of periodic solutions in discrete predator-prey models

This note investigates the existence of periodic solutions for discrete semi-ratio-dependent predator-prey models with functional response. New criteria are derived in which this system with prey-dependent (monotonic or non-monotonic) and predator-dependent functional response bounded by polynomials in R always has at least one omega-periodic solution, which improves and extends many previous results [1-5]. Some interesting numerical examples are given to illustrate our results. (C) 2009 Elsevier Inc. All rights reserved.