Cyclic and non-cyclic dynamics in populations of the helminth parasites of wood mice,Apodemus sylvaticus

Abstract

Two populations ofApodemus sylvaticus, one in deciduous woodland and another in coniferous forest in Co. Down, Northern Ireland, were trapped at monthly intervals over 33 months. The dynamics, reproduction and age structure of the mouse populations differed between years with over a 40 fold range of population size. Nine species of helminths were recovered from the alimentary tract and associated organs of the mice. The prevalence and mean worm burden of the cestodes,Catenotaenia lobata, Hymenolepis hiberniaandTaenia taeniaeformisvaried erratically. The trematodes,Corrigia vittaand to a lesser degreeBrachylaima recurva, had seasonal changes in abundance. The nematodesCapillaria murissylvaticiandNematospiroides dubiushad strongly seasonal cycles of abundance associated with the onset of host reproduction.Trichuris muriswas the rarest helminth. Despite protracted periods of absence this species maintained a seasonal increase in mean worm burden in late winter. The nematode,Syphacia stroma, had a weakly seasonal pattern of dynamics. The bases of these cyclical and non-cyclical dynamics of the helminths ofA. sylvaticusare discussed.