The impact of human land use activities and seasonal changes on dung Beetles (Insecta: Coleoptera) diversity of the Kakamega Forest ecosystem

Abstract

Based on quantitative comparative data collected in the Kakamega Forest and adjacent farmlands between October 2002 and August 2003, analyses were made to ascertain the extent of the different modes of land use, and seasonal changes on the beetle guild structure, abundance and their diversity. Data collection methodology included deposition of 10 standard samples of 1 kg fresh cow dung on standard areas in the various habitats in each season at night and during the day to attract the beetles which were then recovered using the floating method. The 80 samples yielded a total of 21,604 beetles representing the families Scarabaeidae, Hydrphilidae, Staphylinidae and Histeridae. The dominant family Scarabaeidae contained category guild groups of tunnelers, dwellers, and rollers. The studies revealed that the extensive cattle grazing and forest degradation influenced both the guild structure and abundance of the dung beetles. There was high abundance in the grazed grasslands followed by the ungrazed grasslands. All the studied habitats had a significant conditional effect on the beetle family abundance and their guild structure indicating strong association with different habitat locations. Beetle day dwellers were significantly associated with the primary forest, tunnelers with the secondary forest, while rollers and families Staphylinidae and Hydrophilidae were associated with the ungrazed grasslands. Dung beetle assemblages were significantly affected by seasonal changes and human activities. More beetles were collected during the rainy than in the dry seasons. The differences in the beetle guild structure, abundance and species diversity revealed by these studies could be good predictors of susceptibility of habitat degradation for the Kakamega forest by human land uses and seasonal changes