Pollen diversity and protein content in differentially degraded semi-arid landscapes in Kenya

Abstract

In Africa there is a scarcity of information on how plant species that can provide forage for honey bees vary across differentially structured landscapes, and what are the implications of such variabilities on colony integrity. This research presents new insights into the diversity and richness of pollen collected by Apis mellifera scutellata, a subspecies of the Western honey bee native to sub-Saharan Africa, at six study sites of different degradation levels within a semi-arid landscape in Kenya. Ten colonies were established at each site and land cover characteristics were extracted using novel remote sensing methods. The sites differed by the proportions of natural vegetation, cropland, grassland and hedges within each site. Bee bread was collected five times, with three colonies in each of the six sites repeatedly sampled during the period from May 2017 to November 2018. Pollen identification and protein analysis within the study sites were thereafter conducted to establish the linkage between landscape degradation levels and abundance and diversity of pollen. Out of 124 plant species identified, Terminalia spp., Cleome spp. and Acacia spp. were identified as the most abundant species. Moreover, species richness and diversity were highest in the two sites located in moderately degraded landscapes. Pollen protein content showed statistically significant differences across season rather than geographical location. This study demonstrated that landscape degradation negatively affected the diversity and richness of pollen collected by honey bees. Consequently, this helps our understanding of native honey bees’ forage resource usage and plant species preferences in landscapes with varying degrees of degradation.

Keywords:

• Apis mellifera
• landscape degradation
• honey bee nutrition
• natural habitats

Acknowledgements

The authors express their gratitude to the beekeepers in Mwingi for allowing us to locate our apiaries in their farms and for their field assistance. We also wish to acknowledge James N. Kimani for his assistance in data collection and Hosea O. Mokaya for laboratory assistance. Finally, our sincere gratitude goes to Christina M Grozinger, (Pennsylvania State University) for providing training on cutting edge techniques of pollen identification and pollen nutritional analysis. The views expressed herein do not necessarily reflect the official opinion of the donors.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplementary appendices are available via the ‘Supplementary’ tab on the article's online page (https://doi.org/10.1080/10.1080/00218839.2021.1899656).

Additional information

Funding

We gratefully acknowledge the financial support for this research by the National Geographic Society (USA), grant number (WW-194EC-17) which facilitated our field data collection and laboratory analysis. Also, we would like to acknowledge the core financial assistance to icipe by UK’s Foreign, Commonwealth & Development Office (FCDO), the Swedish International Development Cooperation Agency (Sida); the Swiss Agency for Development and Cooperation (SDC); and the governments of Kenya and Ethiopia. Pamela Ochungo was supported by a German Academic Exchange Service (DAAD) In-Region Postgraduate Scholarship.