“…Jiang [29] focused on the permanence and extinction for nonantonomous Lotka-Volterra system. For more research on the permanence behavior of predator-prey models, one can see [8,11,13,14,15,17,18,23]. Here we must point out that most of literatures on these predator-prey models are only connected with parameters which are independent of time delay, while in most applications of delay predator-prey models in population dynamics, the need of incorporation of a time delay is often the result of existence of some stage structure [1,2,9].…”