Dynamics of a host-parasitoid model with Allee effect for the host and parasitoid aggregation

In this paper, a discrete-time host-parasitoid model is investigated. Two biological phenomena, the Allee effect of the host population and the aggregation of the parasitism, are considered in our mathematical model. Through extensive numerical simulations, we gain some interesting findings related to Allee effect from this research. Firstly, the ranges of parameter, in which the population dynamics is chaos, are compressed when Allee effect is added. Secondly, the sensitivity to initial conditions of the host-parasitoid system decreased after adding Allee effect. Thirdly, without Allee effect, we observed two complicated dynamics, intermittent chaos and super-transients. However, when Allee effect is included, these two phenomena are replaced by another kind of phenomenon-period alternation, where chaos is eliminated. From above three novel findings, it can be concluded that dynamic complexities are alleviated by Allee effect. This conclusion is crucial in resolving the discrepancy between real population dynamics and theoretical predictions. Furthermore, the importance of this research is to help us understand the mechanisms inducing the irregular fluctuations of the natural populations. (C) 2009 Elsevier B.V. All rights reserved.