“…Several approaches have been put forward to introduce a Gaussian white noise into deterministic population models. Here, enlightened by the approach used in [4,5,15,17,18,21,25,27,29,30,31,32,33,44,45,52,53,54,55], we consider the parameter perturbation and suppose that the environmental perturbations mainly affect the growth rates of the populations, with r i → r i + σ iẆi (t), where {W i (t)} t≥0 (i = 1, 2, 3) stand for standard independent Brownian motions which are defined on a complete probability space (Ω, F, {F} t≥0 , P ), σ 2 i is the intensity of the white noise. Then we obtain the following stochastic model with delay:…”