Insect mediated pollen dispersal was studied in <i>Althaea officinalis, Succisa pratensis, Chrysanthemum coronarium, Matricaria maritima</i> and <i>Matthiola sinuata</i> using fluorescent dust as a pollen analogue or tracer. The species where chosen because of their different spectra of pollinators, so that the effects on pollen transfer of different behaviour patterns in different insect groups could be assessed. Pollinator behaviour was also studied by direct observation of insects foraging in both natural and artificial plant populations. Individual pollinators were marked in many cases, and both general behaviour patterns, and differences between individuals were studied. Evidence is presented to indicate that foraging insects generally move into the wind, and that pollen flow is therefore generally upwind. Also, most pollen transfers occur within a range of ten metres or often considerably less, although occasional movements to much greater distances are recorded. The behaviour patterns of various insect groups are discussed, with particular emphasis on comparing and contrasting bumblebees, butterflies, moths and hoverflies in terms of constancy, directionality and distance of flight. While many generalisations can be made, it becomes clear that it is also very important to understand that individuality can be significant. Thus, different individuals within a species can often exhibit a degree of constancy or discrimination. In some species this may result in discrimination by the population as a whole, while others may have a homogeneous overall behaviour pattern.

Both low river flows from surface water extraction for irrigation and diffuse nitrogen pollution are agricultural externalities. Efficient environmental regulation at the catchment level requires that the two be considered together. An economic analysis of policies to control non-point source nitrogen pollution in the presence of minimum river flow controls in a Scottish agricultural catchment was undertaken. A realistic nonlinear Bio-Physical Economic model was made to integrate farming practices (crop/soil land allocation, nitrogen fertiliser application, livestock husbandry, surface water extraction for irrigation etc.) with profitability (crop yield) and environmental externalities. Numerous economic, managerial and mixed regulatory policies were ranked on overall reduction in welfare arising from loss of profitability under regulation. The presence of minimum river flow controls in the catchment was found to reduce nitrogen pollution. This reduction was sufficient to be considered in the design of diffuse pollution policies. However river flow controls did not, for the most part, alter the relative ranking of instruments. By themselves, river flow controls were found not be a cost effective means to reduce diffuse pollution. The effect of varying weather patterns on the relative ranking of policies and the levels required to meet the standard was considered. Although the overall efficiency of economic controls targeting emissions was established, mixed instrument policies did particularly well in ‘wet’ weather conditions. While economic controls targeting nitrogen as an input performed poorly in the representative ‘wet’ weather conditions.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

No description available.