Monitoring tenebrionid beetle biodiversity in Namibia

Abstract

Different field methods of determining abundance and species diversity of darkling beetles (Coleoptera, Tenebrionidae) were tested. A combination of the use of pitfall traps and linear transect surveys served as the best rapid assessment of diversity, while pitfall traps alone are good for estimating abundance. Trap size (15cm diameter vs. 10cm diameter) and different degrees of exposure to sun did not significantly affect the capture rate of beetles, which was highly variable between traps at a site, but there were differences between sites and seasons. A minimum of a full year of trapping is required before the slope of the species-effort curve begins to flatten when the most abundant species have been recorded. The curve continues to increase over the course of the next 20 years, by which time all species at a location have been recorded. Furthermore, long trapping periods covers different climatic conditions, reflecting that in the Namib Desert, long-term records are required to study biodiversity.