Discrete Dynamics in Nature and Society
Volume 2006 (2006), Issue 4, Article ID 12176, 21 pages
doi:10.1155/DDNS/2006/12176
Harmless delays in a discrete ratio-dependent periodic predator-prey system
Yong-Hong Fan1
and Wan-Tong Li2
1School of Mathematics and Information, Ludong University, Yantai 264025, Shandong, China
2School of Mathematics and Statistics, Lanzhou University, Lanzhou 730000, Gansu, China
Abstract
Verifiable criteria are established for the existence of positive periodic solutions and permanence of a delayed discrete periodic predator-prey model with Holling-type II functional response N1(k+1)=N1(k)exp{b1(k)−a1(k)N1(k−[τ1])−α1(k)N2(k)/(N1(k)+m(k)N2(k))} and N2(k+1)=N2(k)exp{−b2(k)+α2(k)N1(k−[τ2])/(N1(k−[τ2])+m(k)N2(k−[τ2]))}. Our results show that the delays in the system are harmless for the existence of positive periodic solutions and permanence of the system. In particular our investigation confirms that if the death rate of the predator is rather small as well as the intrinsic growth rate of the prey is relatively large, then the species could coexist in the long run.