Diversity and activity density of bees visiting crop flowers in Kakamega, Western Kenya

Abstract

SummaryWe observed bees visiting bean (Phaseolus vulgaris) flowers, the most widely grown crop in farmland near Kakamega forest, Kenya, which has attracted interest due to the presence of the only remaining tropical rain forest in the country. Two transects were created in the north and south of the forest extending to about eight km into the farmland. Observations were carried out on 14 sites on either side of the forest during the flowering period from April to June in 2005 and 2006. We recorded bees belonging to 20 species visiting beans. The honey bee Apis mellifera L. was the most abundant, followed by two solitary bees, Xylocopa calensand Xylocopa incostans. Bee density was low in the farmland in both sides of the forest, but diversity was significantly (P < 0.05) higher in the southern than in the northern transect. One reason for this is that the southern side is heavily populated so hedges and other land are under higher pressure, giving bees no alternative to crop flowers, whilst in the north, the population is low so there is still much land and hedges for alternative food for bees. Hedge management could be improved to support bees, especially when crops are not in flower, by interconnecting the hedges with the forest, so bees will be able to seek refugia and other needs in the forest and be able to provide pollination in the farmland, hence contributing to food security in the country.