May [20] claimed that fluctuations in the environment would affect the intrinsic growth rate, death rate, carrying capacity, competition coefficients and other parameters involved in the system.
(1.2) where a, K, c, m, f, d are positive constants that stand for prey intrinsic growth rate, carrying capacity, capturing rate, half capturing saturation constant, conversion rate, predator death rate, respectively.
Note that May [2] revealed the fact that due to environmental noises, the birth rate, carrying capacity, competition coefficient and other parameters involved in the system exhibit random fluctuation to a greater or lesser extent.
The parameters r, K, (a_{1}), (a_{2}), d and m are positive constants representing the prey intrinsic growth rate, carrying capacity, capturing rate, conversion rate, the predator death rate and half capturing saturation constant, respectively.
May [16] pointed out that, due to environmental fluctuations, the birth rate, carrying capacity, competition coefficients and other parameters involved in the system exhibit random fluctuation to a greater or lesser extent (see [17 20]).
where x 1 and x 2 denote prey and predator densities, respectively; r, K, α, β, d, γ are positive constants that stand for prey intrinsic growth rate, carrying capacity, conversion rate, half capturing saturation, the death rate of the predator, the harvesting rate of the predator, respectively.
