The effect of pollen amount and its caloric value in hybrid lucerne (Medicago x varia) on its attractiveness to bumble bees (Bombus terrestris)
¹Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences,Kreutzwaldi St. 64, Tartu 51014, Estonia; e-mail: reet.karise@emu.ee
²Institute of Sustainable technology at Tallinn University of Technology,Akadeemia 4, Tartu 51003
³Jõgeva Plant Breeding Institute, 48309 Jõgeva, Estonia
Abstract:
Bumble bees forage for pollen and nectar on various plant species, but individuals often restrict their choice to a few flower types. The aim of this work was to study whether there is variation in certain pollen characteristics between differently coloured flowers of hybrid lucerne and whether this could be the reason why bumble bees prefer one flower type to another. The pollen amount, pollen grain size and the caloric values from different flower types were analysed to study the reasons for flower colour preference. On two cultivars of hybrid lucerne (Medicago x varia Mart.) the yellow flowers were preferred, but the reasons for the preference differed.
Key words:
bumble bees, caloric value, colour morphs, Medicago x varia, pollen amount