The influence of climate on the activity patterns and abundance of Xerophilous Namib desert dune insects

Abstract

The basis of this thesis is a trapping experiment conducted over one year (1969). Unbaited pit traps were placed in the most important habitats of a Namib Desert dune system and were checked and emptied daily. The traps were spread over the area in such a way as to ensure that total number of catches was representative of the total area, i.e. number of traps in a specific habitat was proportional to the relative surface area of this habitat within the total area. While other animals were also trapped, this study is restricted to wingless terrestrial insects. A total of 47 species of terrestrial insects was recorded in the area, of which more than half belong to the family Tenebrionidae. At least five new taxa of the Arthropoda were discovered in this area in the course of the survey. Daily catches of the 47 species dealt with, were studied in relation to daily measurements of wind, maximum and minimum temperature, and precipitation in order to discover possible correlations. The total catches of every species in the various habitats were used for constructing distribution histograms of these species within the experimental area. The technique of trapping developed for this survey provides comparable data on time of day, time of year, and place of activity of the various terrestrial species. A trap developed for this purpose is described. An integrated picture of the ecology of the Namlb Desert dune area, which is unique in the world for its rich variety of desert-adapted species, is constructed on the basis of the data collected during this survey.