THE VERTICAL-DISTRIBUTION OF CULICOIDES IMPUNCTATUS LARVAE

Soil cores were taken from three transects, representing the vegetatio n typical of much of the west coast and Highlands of Scotland, in an a ttempt to investigate the distribution of Culicoides impunctatus larva e. Sampling of soil cores was carried out at four periods throughout t he day (00.00, 05.00, 12.00 and 17.00 hours). Each core sample was sli ced into sections, 1 cm deep and Culicoides impunctatus larval numbers in the first 8 cm of the soil core were investigated, using a sugar-f lotation technique. At all sampling times, approximately 50% of the to tal numbers of larvae recovered were from the first 2 cm of the soil. During the daylight sampling periods (05.00, 12.00 and 17.00 hours), t here was a small but significant migration of larvae into the deeper l ayers (2-5 cm). The results are discussed in relation to those for oth er species from previous studies, and also to their application in lar val collection for colonization techniques and in localized Culicoides control.