THE DISTRIBUTION AND POPULATION REGULATION OF THE WOOD MOUSE APODEMUS-SYLVATICUS ON FIELD BOUNDARIES OF PASTORAL FARMLAND

1. The population characteristics and distribution of wood mice Apodemus sylvaticus (L.) were investigated along field margins of farmland dominated by grass production. 2. Turnover, sex ratio, breeding season, spatial density dependence and density dependence in reproductive activity indicated that the population ecology of A. sylvaticus is consistent in different habitats in the same geographical region. 3. Spatial variation in the abundance of A.sylvaticus was related negatively to percentage of land under pasture and distance from woodland and positively related to variables associated with food supply and cover. 4. Variation in numbers of overwintered mice at the start of the breeding season was related more closely to breeding opportunity than to environmental factors. This was particularly so in males. 5. The association of overwintered male and female A. sylvaticus remained evident in the later half of the breeding season. Young males and females of the year, however, were distributed more with respect to physical and biological features than towards adults or reproductive opportunity. 6. A. sylvaticus is an important species of field margins, even where these are poorly developed and agriculture is pastoral rather than arable. Further studies of this species in a wider range of agricultural systems are desirable.

THE DISTRIBUTION AND UTILIZATION OF ZOSTERA SPECIES IN STRANGFORD LOUGH, NORTHERN-IRELAND

Strangford Lough is a sheltered marine inlet on the east coast of Co. Down, Northern Ireland. The distribution of Zostera in the Lough and its exploitation by wildfowl was investigated. There was an estimated 1100 tonnes (fresh weight) of Zostera in the Lough in October 1991 covering some 6.3 km2 of the northern mudflats and representing some 12% of the total intertidal area of the Lough. This was regarded as peak biomass. By January 1992, Zostera was reduced following grazing by wildfowl and weathering to 20% of the initial biomass as measured in the exclusion experiment. The above-ground and below-ground biomass of Zostera were not equally affected with reduction to 7% and 26%, respectively.

THE EFFECT OF DIAMPHENETHIDE ON PROTEIN-SYNTHESIS BY THE LIVER FLUKE, FASCIOLA-HEPATICA

The effect of the deacetylated (amine) metabolite of diamphenethide (DAMD, 10 mug ml-1) on the uptake and incorporation by adult Fasciola hepatica of radioactively labelled precursors of DNA, RNA and protein synthesis ([H-3]thymidine, [H-3]uridine and [H-3]leucine, respectively) was measured by liquid scintillation counting. Comparison was made between the effects of DAMD and those of specific inhibitors of DNA, RNA and protein synthesis, namely, 5-fluorouracil, cordycepin and cycloheximide, respectively. DAMD caused a significant decrease in the overall uptake and incorporation of [H-3]uridine by F. hepatica, decreased the incorporation of [H-3]leucine and also caused a significant decrease in the overall protein content of the flukes. The effect of DAMD was similar to that of cycloheximide (I x 10(-3) M), a potent inhibitor of protein synthesis, which also caused a significant decrease in the incorporation of [H-3]leucine by the fluke and a decrease in the overall protein content of the fluke. Cordycepin(100 mug ml-1) caused a significant decrease in the protein content of the fluke, but had no effect on the uptake or incorporation of [H-3]uridine. 5-Fluorouracil (I x 10(-4) m) did not affect the uptake or incorporation of VH]thymidine, nor did it decrease the protein content of the fluke. The results indicate that DAMD inhibits protein synthesis by F. hepatica, possibly by inhibiting RNA synthesis. The results are also consistent with previous morphological investigations involving DAMD.

POPULATION BIOLOGY OF HELIGMOSOMOIDES-POLYGYRUS (NEMATODA) IN THE WOOD MOUSE

1. This paper examines the interaction between the wood mouse, Apodemus sylvaticus L., and the intestinal nematode, Heligmosomoides polygyrus Dujardin, using data collected at Tollymore Park Forest, Co. Down, Northern Ireland, between November 1978 and July 1981.

QUANTIFICATION AND PARTIAL CHARACTERIZATION OF REGULATORY PEPTIDES IN THE LIVER FLUKE, FASCIOLA-HEPATICA, FROM DIFFERENT MAMMALIAN HOSTS

1. Extracts of the liver fluke, Fasciola hepatica from three different hosts (cow, sheep, rat) have been subjected to radioimmunoassay using antisera to 6 mammalian regulatory peptides.

INTRAPOPULATION VARIATION IN THE DIET OF THE WOOD MOUSE APODEMUS-SYLVATICUS

Variation in the diet of wood mice, Apodemus sylvaticus, was investigated in two contrasting habitats, deciduous and coniferous woodland, over 26 months and in 10 additional sites trapped during winter. Stomach contents were categorized as seed, fruit, green plant, root and animal material. Diet was evaluated using the percentage occurrence of each food type. Age and sex differences in diet occurred infrequently. Seed predominated throughout but was especially prevalent in autumn and winter. There was a peak in the incidence of animal material in the spring and early summer. Animal food was generally more frequent in mice caught in conifer plantations than in deciduous woodland during the longer-term study. Further, mice from the additional coniferous habitats had greater percentage occurrence of animal food than those from the additional deciduous sites. There was a negative, non-linear association between relative population size and diet in these winter samples. This suggests that spatial variation in numbers of A. sylvaticus is dictated by food availability and density is locally food limited.