Predator's dietary response to prey density variation and consequences for a cestode transmission
Résumé
Functional response of predators to prey density variations has been already documented to understand predation patterns. However, the consequences of functional response on parasite transmission remain largely unexplored. The rodents Microtus arvalis and Arvicola terrestris are the main preys of the red fox Vulpes vulpes in eastern France. These species are intermediate and definitive hosts of the cestode Echinococcus multilocularis. We explored fox dietary and contamination responses to prey density variations. The dietary response differed between the two prey species: no response for M. arvalis and a type-III like (sigmoidal) response for A. terrestris with a possible interference with M. arvalis. Fox contamination response followed a type-II shape (asymptotic) for both species. We conclude that fox predation is species-specific and E. multilocularis transmission is likely to be regulated by a complex combination of predation and immunological factors. These results should provide clues to better understand biological and ecological mechanisms involved in the transmission dynamics of trophically transmitted parasites when multiple hosts are involved. Also the relevance of models of parasite transmission should be enhanced if non-linear patterns are taken into account.