No abstract

Summary1. Parasite transmission frequently depends on an intermediate host species being subject to predation by a definitive host. We hypothesized that the population dynamics of this type of parasite would be affected by plasticity of the predation behaviour of the final host. The zoonotic tapeworm Echinococcus multilocularisLeuckart is transmitted to foxes ( Vulpes vulpes L.) by predation on infected rodents. One possible mechanism underlying the significant decrease in the prevalence of E. multilocularis in red foxes observed towards the centre of Zurich (Switzerland) is that the relative abundance of intermediate hosts varies between different urbanized habitats. 3. The water vole, Arvicola terrestris scherman L., which is the major intermediate host, was less abundant in urban compared with peri-urban areas, due to both a reduced availability of suitable habitats and lower numbers within those habitats. Stomach content analyses indicated that foxes in urban areas consumed more anthropogenic food but preyed less frequently on rodents -and those rodents taken belonged to species less susceptible to E. multilocularis infection. 4. We conclude that the functional response of final hosts to changes in supply of intermediate hosts and alternative food sources can significantly affect the transmission dynamic of dixenous parasites, such as this zoonotic tapeworm.