THE MICROHABITAT OF CULICOIDES-IMPUNCTATUS (DIPTERA, CERATOPOGONIDAE)LARVAE IN SCOTLAND

Soil samples were taken from two transects (total 63 sampling points; 25 cm quadrats) representing the Betula pubescens (Betulaceae) woodlan d, rush-pasture and peat-based mire vegetation of the west coast and H ighlands of Scotland, in an attempt to relate soil and vegetation feat ures to the occurrence of Culicoides impunctatus Goetghebuer larvae. T he covers of vegetation groups were recorded at each sample site and s oil wetness was assessed on an arbitrary scale. Culicoides spp. larvae were extracted from half of each sample and stored for subsequent ide ntification of C. impunctatus larvae, while the remaining half was use d for analysis of soil pH and organic content (loss on ignition, LOI). Correspondence analysis (using DECORANA) separated the sample sites a nd vegetation groups and the ordination axes were significantly correl ated with the density of C. impunctatus larvae, soil organic content a nd soil wetness index. Simple regression analyses revealed that the de nsity of Juncus acutiflorus/J. articulatus (Juncaceae) and soil wetnes s index were positively related to the overall variation in C. impunct atus larval density. The wetness index had the strongest relationship and this remained the case in step-wise multiple regression. There was no relationship between larval density and soil pH. This information on the specific microhabitat preferences of the larvae could aid colon ization attempts of this dominantly important species of biting midge in the UK.