A host-parasitoid interaction with Allee effects on the host

We explore the addition of Allee effects to single-species discrete-time models with overcompensatory density dependence. When the intrinsic growth rate of the population, r, is large, the population bifurcates into chaos. The population goes extinct if r is either below a threshold level or very large. The model is then used to study host-parasitoid interactions with and without Allee effects in the host. The coexistence of the host and parasitoid populations both depends on threshold levels of r, threshold levels of the host population size, and the parasitoid potential, which is the product of the searching efficiency of the parasitoid for the host, and the fecundity of the parasitoid. The addition of Allee effects has a negative impact on the coexistence of both populations. (c) 2007 Published by Elsevier Ltd