“…As is well-known, the population dynamics in the natural world is unavoidable affected by environmental noises. Usually, in the process of mathematical modelling, we assume that the growth rate of species is subject to environmental random noise (see [7,10,11,13,19,23,24,27]). That is to say, we assume that r i → r i + σ i dB i (t) (i = 1, 2, 3) in the following system, where B i (t) (i = 1, 2, 3) are standard independent Brownian motions defined on the complete probability space ( , {F t } t≥0 , P) with a filtration {F t } t≥0 satisfying the usual conditions, and σ 2 i (i = 1, 2, 3) is the intensity of B i (t).…”