Medicinal leeches (Hirudo medicinalis) attacking and killing adult amphibians

Although the relative importance of different nal leeches. In two serological studies, 86% and factors regulating amphibian populations is not 24% of examined leeches were found to have fed very well understood, predation and parasitism on amphibians (Wilkin & Scofield 1990, Keim are thought be important elements in shaping 1993, respectively). Although these numbers amphibian life-histories and, perhaps, population do not provide any indications about the conse dynamics (Beebee 1996). However, relatively quences of leech parasitism for amphibians, pub little is known about the impact of parasitic lished anecdotal observations testify to poten infections on fitness of individual amphibians tially drastic effects. Populations of frogs, toads (but see: Goater & Ward 1992, Strijbosch 1980, and newts in different parts of Europe have been Tocque 1993), or their impact on amphibian popreported to suffer dramatic mortality following ulation dynamics and persistence. With this note, leech attacks (Table 1). For instance, Sahlin we wish draw attention to one particular parasite, (1930) reports medicinal leeches infecting both the medicinal leech (Hirudo medicinalis), which spawning common frogs (Rana temporaria) and might be a locally important source of mortality moor frogs (R. arvalis) in Targe numbers' in for adult amphibians. southern Sweden. Similar observations are avail The medicinal leech feeds on vertebrate able from more recent times: Hoffmann (1960) blood, and the long-held view in the literature reported common toads (Bufo bufo) in one par has been that mammals are their main hosts ticular pond in Luxembourg being so heavily and mammalian blood is required for successparasitised by medicinal leeches that no female ful reproduction (e.g. Forselius 1952). However, survived to reproduce during the five-year period field observations (Table 1) together with recent the pond was monitored. Likewise, attacks lead serological investigations (Wilkin & Scofield ing to the death of large numbers of smooth 1990, Keim 1993) indicate that adult amphibians newts (Triturus vulgaris) have been reported in may constitute an important resource for medicitwo studies (Table 1). Many of these observa