Dr. Murai Éva szerk.: Parasitologia Hungarica 25. (Budapest, 1992)

that the prevalence and mean intensity peaks ofH. laevis, S. nigeriana, P omphalodes and A. dentata did not add up. Generally, T. taeniaeformis larva and P janickii also caused a low infection. Comparing the prevalence and intensity profiles by sex, a difference was observed in the composition of the recovered helminths (Fig. 5, Fig. 6). Infection by T. muris was seen in one female specimens only. The prevalence of H. laevis reached the maximum in older (30 < g) females. P omphalodes and P. janickii also showed the highest prevalence in this category. Infection by T. muris, H. horrida, H. asymmetrica and T. mustelae was found in one weight category each. 5. nigeriana and T. taeniaeformis larva were recovered from different weight classes, but they were absent from older animals. The prevalence of T. taeniaeformis larva also exceeded 10 %. Primarily H. laevis was responsible for the maximum of general intensity, attained in 20-24 g females. P. omphalodes showed the highest value of mean intensity in 20-24 g females. Of the other species recovered, only S. nigeriana was noteworthy. On the other hand, an opposite trend in the prevalence and mean intensity of H. laevis was demonstrated as a function of female host weight (Fig. 6). DISCUSSION In the literature this is the first report of A. microps as a new host species for Anoplocephaloides dentata, Hymenolepis fraterna, Hymenolepis diminuta and Hymenolepis muris-sylvatici (cf. Tenora and Mészáros 1975, Murai 1982, Matskási et al. 1990). The prevalence of A. dentata was generally very low (1%) in A. microps. However, it is a well-known cestode of microtid species (Murai 1974, Tenora and Murai 1980). Before this study, H. fraterna had not been recovered from the small field mouse living in the Carpathian basin (cf. Murai 1972, Tenora and Murai 1980, Tenora et al. 1980). This and the other hymenolepid cestode, H. diminuta showed a low prevalence (2.05, and 1.02 %, respectively), similar to that obtained for A sylvaticus and A. agrárius (cf. Murai 1972, Tenora and Murai 1972, see Table 4). The above authors emphasized that H muris-sylvatici is identical with H. crenata parasitizing birds (Passeriformes). The maximum and profile of general prevalence and intensity were observed in the same weight category. According to our investigation, adult mice seemed to have a higher infection rate than did younger ones. On the other hand a higher intensity of infection was found in juvenile animals. Numerous contradictory data exist on susceptibility varying by sex (see Gregory 1992 for a review). The present study has confirmed the results of previous field studies, i. e. that male host are more susceptible than females (cf. Lewis 1968, Lewis and Twigg 1972). These findings may be associated with the different growth profile, feeding habits, reproductive condition and neuroendocrine background of the two sexes. Different characteristics were recognized in the profile of helminth infections. H. polygyrus appeared with an explosion-like invasion in older females (18-20 g), with concurrent peaks of prevalence and mean intensity. This feature was observed also in