Effects of habitat biotic features on hymenopteran diversity in East Africa

Abstract

Abstract Purpose Originally, the coastal region of East Africa was largely covered with coastal forest. With the human settlement, the majority of these forests have been transformed into agricultural land for subsistence farming. Today, only small and geographically isolated forest remnants exist and form a mosaic of different habitat types, including natural, semi-natural and anthropogenic ones. The forest remnants may still represent valuable habitats for typical forest plant and animal species. Methods In this study, we surveyed hymenopteran diversity and community composition in different habitat types in southern Kenya. Hereby we considered a small remnant of East African coastal forest, adjoining orchards, shrublands, tree plantations, agricultural fields, and settlements. Hymenoptera represent a large variety of taxa and provide relevant ecosystem services such as pollination to the local people. Hymenoptera were collected with coloured pan traps, identified to family or genus level, and sorted to morphospecies. Habitat parameters such as dead wood, leaf litter, vegetation structure, and the availability of flowers has been assessed for each study site. Results In total, we found 419 Hymenoptera individuals of 153 morphospecies. The different habitat types showed distinct species communities of Hymenoptera. Increasing shrub layer and increasing herb cover had a negative effect on hymenopteran species richness and abundance. Flowers, trees, leave litter, and deadwood showed no significant effect on hymenopteran diversity. Conclusion Our results underline that small-scale habitat diversity lead to high overall diversity of Hymenoptera. Implications for insect conservation: The coastal forest remnant still holds a unique hymenopteran community with 20 Hymenoptera species exclusively found in this habitat type. It is thus of very high conservation value.