Unusual multiparasitism causes overweight in a wood mouse, Apodemus sylvaticus (Rodentia: Muridae), from a post-fire regeneration area

摘要

Multiparasitism is a common ecological phenomenon, being the norm rather than the exception, in the wild. This article describes the case of a wood mouse, Apodemus sylvaticus, originating from a post-fire regeneration area, infected with multiple helminth species and remarkable overweight. The mouse analyzed was captured at a post-fire regeneration site in the Serra Calderona Natural Park (Comunitat Valenciana, Spain). The rodent was captured and marked for the first time in the spring of 2011, weighing 22.5 g. When it was recaptured in the winter of 2012, it weighed 44.0 g. The mouse was parasitized by a total of 31 helminths belonging to seven species, including six Taenia parva metacestodes. These tapeworm juveniles reached a weight of 12.0 g, more than 25 % of the host's weight. Therefore, multiple parasitism should be considered the real cause of its elevated weight. Although only one case of this unusual overweight has been found in this post-fire regeneration area, it, nevertheless, supports the theory that ecosystem instability can induce unusual situations in the parasite-host system.