Processes influencing the duration and decline of epizootics in Schistocephalus solidus.

The interplay of intermediate host fish and plerocercoids of diphyllobothriidean cestodes results in epizootics that are deceptively simple, but conceal complex biotic and abiotic interactions shaping each event independently. Although general descriptions of epizootics and some details of biotic interactions between enemies are known, much remains to be discovered about the abiotic and biotic forces and their interactions driving epizootics. This study shows that the duration of an epizootic of Schistocephalus solidus was sustained by high prevalence, mean intensity, and PI (parasite index-parasite : host biomass ratio) levels among young-of-the-year and 1-yr-old threespine sticklebacks.