Studies on the possible competition for pollen between the honey bee, Apis mellifera sudanensis, and the imported dwarf honey bee Apis florea (Hym., Apidae) in North-Khartoum (Sudan)

Based on identification of collected pollen, in the area of North Khartoum, 21 plant genera (ca. 21 spp.) proved to be the main pollen sources for the honey bee Apis mellifera sudanensis. The imported dwarf honey bee Apis florea exploited 11 of these. The main pollen flow in the study area occurred between early December and late March. This is reflected by the amount of pollen collected by colonies of A. mellifera sudanensis. In spite of observations conducted soon after the introduction of A. florea, which gave hints of competition between the two bee species, further studies showed that A. mellifera sudanensis and A. florea do seem to coexist. This coexistence is based on different daily rhythms of pollen collection. A. mellifera collected pollen of Acacia seyal, date palm, and onions early in the morning ( and partly in the late afternoon), while A. florea started pollen collection mostly later in the morning and ended it earlier in the afternoon. But in contrast to A. mellifera, A. florea was collecting pollen all day without interruption, even at very high air temperatures. Niche overlap ( concerning the times of visits to flowers) between the two bee species was very low in date palms, and of medium importance in Acacia seyal. But it is remarkable that in total, A. florea is always present in higher numbers than A. mellifera sudanensis, on flowers. The significance of the introduction of A. florea to Sudan for pollination is discussed.