Abstract. Because rodents behave cryptically and often have large home ranges, the role of social defence in determining their spatial dispersion in grassland remains an enigma. Individual dispersion and access to resources could be determined mainly by the aggressive exclusion of intruders from large territories by residents, or by the scattered distribution of resources and avoidance of dominant competitors occupying preferred sites. The ways in which predictions from these two hypotheses correspond to intra-sexual competitive behaviour within unfamiliar dyads of the mouse Mus spretus, recently captured from two grassland populations, were examined. A series of tests in enclosures examined (1) exploration by intruders given a choice between a resident's soiled sites versus clean sites, or between resident-soiled sites versus sites bearing their own odour, in the absence of the resident; (2) the response of an intruder on meeting either the resident or another mouse, in an adjacent clean tunnel; and (3) the response of a resident to an intruder compared with mice meeting in a clean enclosure. In both sexes, dyads quickly established dominance relationships through brief attacks and chases, and static defensive postures, rather than persistent pursuit and flight. Intruders were strongly attracted to a resident's nest and subsequently were more aggressive towards the resident than towards an opponent from an unfamiliar enclosure. There was less differentiation in competitive behaviour and more mutual fighting between residents and intruders than between mice in clean enclosures, with relative body weight being the most important factor determining competitive behaviour. The results were thus more consistent with competition for dominance over suitable sites than investment in fierce aggression to drive competitors away.

R unoff from agricultural land carries sediment and nutrients that can harm receiving water quality and degrade land productivity. Infiltration capacity and surface hydraulic conductivity of the soil is a principal factor in determining the amount of runoff resulting from a rainfall or irrigation event. Surface application of livestock manures alters surface hydraulic conductivity by forming a short-term soil-plugging effect, which reduces infiltration capacity and by acting as a longterm soil conditioner which improves the infiltration capacity. Hydrologic models are valuable tools in determining the effects of land-use practices on hydrology and water quality. To successfully model hydrologic responses and thus identify best management practices, a complete understanding of the infiltration process is necessary. This understanding must include the effects of agricultural practices such as tillage, manure application, etc., on infiltration. The hydrologic models must be adapted to changing soil surface conditions that are affected by altered agricultural practices and changing environmental conditions. The goal of this study was to determine the effect of livestock manure application on surface-seal formation. The specific objective was to review existing infiltration models that have been adapted for surface sealing or crust formation and to modify these models to predict water infiltration through the surface seal formed by manure application. The scope of this study required a nondestructive method for determining surface-seal properties of manure-amended soils. Modifications of these models will aid consultants and regulators dealing with manure application and water-quality issues in decisionmaking processes. LITERATURE REVIEW Many researchers have observed that a thin layer of reduced permeability forms on the surface of soil exposed to rainfall (Duley, 1939; McIntyre, 1958; Tackett and Pearson, 1965). This distinct layer is characterized by higher bulk density and lower porosity than the underlying soil. The term "surface seal" is commonly used to describe the effect this layer of reduced permeability has on limiting infiltration. Upon drying, the seal shrinks to form a hard crust that impedes seedling emergence and tears seedling roots as the seal cracks (Hillel, 1980). Knowledge of surface-sealing properties is required to model infiltration through a surface seal. Prediction of surface-seal characteristics is difficult, since surface-seal development is a function of several factors, including texture, initial bulk density, aggregate stability, initial shear strength, organic matter, tillage, and land-use practices (Sharma, 1980; Rawls et al., 1990), as well as rainfall intensity, second moment of drop-size density distribution, and maximal drop diameter (Assouline and Mualem, 1997). Little data has been published regarding surfacesealing characteristics in manure-amended soils. Many approaches have been proposed to describe infiltration through a stable surface seal. Hillel and Gardner (1970) conclude...

iThe presence of the South American pasture beetle Plectris aliena Chapin in Australia near Casino, New South Wales, is reported.Characters of use in distinguishing the adult and larval stages from those of native scarabaeids are described. The bionomics, ecology, and potential importance of the species are discussed.It is concluded that P. aliena is a species of humid‐temperate climates where it appears to be restricted to light sandy soils. The larvae may damage the roots of grasses and crops.

The survival and liveweight gain of Rhopaea morbillosa and Anoplognathus spp. larvae were determined in pot experiments over 9 weeks. Liveweight gain was greatest at soil moistures about two‐thirds field capacity, and where 4% of soil was replaced with manure. Trifolium repens caused a significant reduction in liveweight gain compared with grasses. The reduction of liveweight gain in the absence of plants was not significant. Increased soil moisture caused a decline in survival, and the addition of manure to soil increased survival. Phalaris tuberosa tended to cause high mortality in Rhopaea. Trifolium and Phalaris caused more than half the Anoplognathus to fail to pupate. RÉSUMÉ INFLUENCE DES PLANTES, DU FUMIER ET DE L'HUMIDITÉ DU SOL SUR LA SURVIE ET LE GAIN EN POIDS VIF DE DEUX LARVES DE SCARABAEIDES La survie et le gain en poids vif de Rhopaea morbillosa Blackburn (Melolonthinae, Coleo‐ptera) et de Anoplognathus spp. (Rutelinae, Coleoptera) ont été déterminés par des essais en pots durant une période de neuf semaines. Le gain en poids vif le plus important a été obtenu avec des humidités du sol situées aux environs des deux tiers de la capacité au champ, et quand on ajoutait 4% de fumier (en poids) au sol. Les gains ont été les mêmes pour les deux espèces de scarabaeides avec Dactylis glomerata, Festuca arundinacea et Lolium perenne. Avec Phalaris les gains avaient tendance a être plus réduits qu'avec les trois autres herbes. Trifolium repens a provoqué une réduction significative de la vitesse de croissance des larves du deuxième Stade de Anoplognathus et des larves du troisième stade de Rhopaea, par comparaison avec Dactylis et Lolium. Avec Trifolium et Phalaris sans fumier, plus de la moitié des larves d'Anoplognathus ne réussirent pas à se métamorphoser en nymphes. Le gain en poids vif de R. morbillosa n'était pas réduit d'une façon plus significative en l'absence de plantes. Une augmentation de l'humidité du sol a provoqué une diminution de la survie. et des additions de fumier I'augmentèrent. La survie des larves du deuxième et du troisième Stades de R. morbillosa fut limitée avec Phalaris en l'absence de fumier, par contre la survie avec Trifolium fut de 100% pour les deux Stades larvaires. La survie des larves du second stade d'Anoplognathus a été faible avec Trifolium sans fumier.