Diversity and distribution of bees in selected districts of Central Uganda

Abstract

Bees play a vital role in maintaining ecosystem functioning and agricultural productivity through pollination. However, their diversity and distribution are increasingly threatened by habitat degradation, land use changes, and unsustainable agricultural practices. This study investigated the diversity and distribution of bees in selected districts of Central Uganda, analysed the key environmental factors influencing their occurrence, and evaluated the effectiveness of different sampling methods for studying bee diversity. Data were collected from farmland, woodland, and grassland habitats using two sampling techniques, including pan traps and sweep nets, across both wet and dry seasons. Vegetation characteristics, including tree, shrub, herb, and grass cover, were also assessed to determine their influence on bee diversity and composition. Identification for some specimens was carried out to the genus and for others to species level. Diversity indices, ordination analyses, and complementarity assessments were applied to quantify community structure and sampling efficiency. A total of 112 species representing 47 genera and four bee families (Apidae, Colletidae, Halictidae, and Megachilidae) were recorded. Farmland supported the highest bee richness and abundance, likely due to habitat heterogeneity and floral diversity, while woodland and grassland harboured rare and habitat-specific species. Redundancy analysis revealed that herb and grass cover were more strongly associated with bee diversity than tree and shrub cover, suggesting dominance of generalist species that tolerate varying vegetation structures. Seasonal variation influenced genus composition. sweep nets captured a higher number of species and individuals than pan traps. Still, both methods exhibited partial overlap, indicating that combining them yields a more comprehensive assessment of bee communities. In conclusion, bee diversity in Central Uganda is shaped by habitat heterogeneity and vegetation cover, with herbaceous and grass cover providing essential foraging and nesting resources. The findings underscore the need to conserve a diversity of habitats, especially farmlands integrated with natural vegetation to support and sustain bee populations. It is recommended that future research adopt long-term, multi-seasonal monitoring using complementary sampling methods to improve species detection accuracy. Furthermore, local communities should be sensitised on sustainable land use practices that enhance floral diversity to promote bee conservation and pollination services.