Influence of parasitized adult reproduction on host-parasitoid dynamics: An age-structured model

In this work, we develop an age-structured model (based on delay-differenti al equations) to investigate the dynamics of host-parasitoid systems in whi ch adults are the target of parasitism. The rare previous work dealing with such interactions assumes that hosts are functionally dead as soon as they are attacked. We relax this assumption and show that low reproduction rate s of parasitized hosts can promote stability at the expense of cyclic behav ior (either long term or generation cycles). Higher reproduction rates make the regulation of the host population by parasitoids impossible. As it is the case in models in which adults are subjected to attacks but do not repr oduce, our model generates generation cycles for a larger set of parameter values than in models in which juveniles are attacked. (C) 2000 Academic Pr ess.