Foraging behavior of Osmia cornifrons in an apple orchard

An apple orchard consisting of a single commercial cultivar and of pollinizers such as Crab apples under the condition of natural pollination needs pollinators for stable fruit production. We investigated the foraging behavior of pollinators, especially Osmia cornifrons Radoszkowski, in order to evaluate their use instead of honeybees.O. cornifrons showed strong flower constancy for 4–8 min during one pollen–nectar foraging trip, as observed in honeybees. However, the bees seemed to forage for different types of flowers, e.g. from a red to a white petal color, during their 16–22 pollen–nectar foraging trips based on the S-RNase allele and simple sequence repeat (SSR) analyses of pollen loaves made during those trips. After one pollen–nectar foraging trip, the bees brushed their abdomen with their hind legs at a nester tube, but ca. 10% of pollen was not brushed from their bodies. The remaining pollen on the body retained the ability for the fertilization of apple for 12 days, suggesting that the pollen on the pollinator's body from a pollinizer could be used for the fertilization of a commercial cultivar visited on their next foraging trip.O. cornifrons seems to be a useful pollinator in apple orchards consisting of a single cultivar, such as, ‘Fuji’, and of pollinizers of different types, such as the red petal color type, ‘Maypole’ or ‘Makamik’. Moreover, most pollen loaves investigated contained S28-RNase allele, which was specific for pollen of ‘Starking Delicious’ planted at a great distance (55.2 m) from the nestiny shelter, suggesting that O. cornifrons is a useful pollinator for ‘Delicious’, which is difficult for honeybees to use as a pollinator for its sideworking behavior.