Bee biodiversity and their forage-plant resources in Queen Elizabeth National Park

Abstract

Knowledge on bee ecology and diversity in the different habitats of Africa and East Africa in particular, are still very limited. In Uganda published studies on bee diversity and community composition in representative habitats, are only a handful. This study determined bee community composition, diversity and their forage resources in the wooded grasslands of Queen Elizabeth National Park (QENP). The park is located in the Albertine Rift, a very important Biodiversity Hot spot on the African continent. Bees and their forage plants were sampled from six sites, from March to July, 2008. Sampling for bees was done using two methods; Transect Survey, for six rounds and Pan Traps, for seven rounds. The flowering plants, on which bees were observed foraging or perched during transect surveys, were also noted. Taxonomic identity and diversity indices of the bee fauna were determined and investigated in relation to sampling methods and other measured environmental variables with a bearing on foraging and nesting needs of bees. A total of 2,484 individual bees, representing three families, 20 genera and 51 morpho species, were collected. Apidae was the most abundant and genus rich family followed by Halictidae and Megachilidae. Halictidae however, had the highest number of morpho species. The most abundant bee genera were Lasioglossum, Baunsapis and Hypotigona, making up 60% of the sampled bees. Three of the represented genera i.e. Thrinchostoma, Seladonia and Steganomus have not been reported anywhere else in Uganda. It was found out that a small fraction of taxa dominated the bee fauna, and over 70% were incidental. A smaller pattern was observed with frequency of occurrence (rarity) and a strong correlation was observed between dominancy and rarity of bee species. Diversity measurements were not significantly different across the study sites probably because the observed differences between sites were not strong enough to cause significant changes in their bee communities. Significance was however observed with bee abundance (x2 = 37.795, P<0.01, d.f =5) across sites, probably because of the differences in the forage resource base. The size of thicket clumps, forage resource and Shrub cover were noted to predict bee community composition in QENP. Forage plant resources were dominated by shrubby species and the most important of which were Ocimum sp., Grewia similis, and Abutilon guineense.