Observations on the Foraging Behaviors of Commercial Bumble Bee Colonies in Prunus avium Orchards

Abstract

Prunus avium blooming period starts in early spring. The uncertain climatic conditions in this period can cause mis-pollination syndromes. It could be directly because of the frozen days or non-forgeable conditions for the possible pollinators or indirectly the poor quality of surrounding habitat and lack of pollinators. When wild pollinators are scarce owing to one of these reasons, introduction of commercial pollinators can be a solution to ensure pollination. Within this context, commercial bombus colonies were chosen as insurance for the pollination of sweet cherries. In the blooming period of Prunus avium, for two years-with totally 120 transect observations, the daily foraging activities of these bumblebees were investigated in Sultandağı-Afyonkarahisar. Before the settlement of the hives in the field, trees were marked with different colored stripes every 10 meters which makes it possible to follow how far the bumblebees fly and forage in the field. Starting at 7:00, 9:00, 11:00, 14:00, 16:00, and 18:00, six times a day, with transect observations, the number of the foragers on cherries was recorded. The average number of flowers they visit per minute was calculated. The plants blooming simultaneously with cherry trees in the trial area were determined. Pollen preferences of foragers were examined with their cobicular pollen loads. The actual foraging range was found as 10-40 meters away from the hives, the maximum activities were recorded before the noon. The average number of visited flowers per minute for bumblebees was ~ 8 flowers. Taraxacum spp. and Lamium spp. pollen were found, but cherry preference was determined to be almost 90%. It is still an uncommon agricultural practice to use commercial bumble bees in open fields, especially for the plants which have very early blooming periods in early spring, it is thought that they are very good manageable pollinator agents according to their foraging capacities.