With the first warm spring days, thoughts of the beautiful things of the warm seasons come to mind: summer sun, beach, and outdoor fun. What of course should not be missing in such weather is cool ice cream. The classic ice cream in the ice cream cone made from dairy is particularly popular here. A sweet and delicious treat for young and old. What hardly anyone thinks about, however, is the long chain of production steps that precede this summer fun. And it doesn’t start with the cows that provide the milk for cream production, it is the bees. They ensure the pollination of the plants that serve the cows as a source of food and thus form the basis of all dairy products. And here the bees sometimes have a really bad job. The flowering meadows with buzzing bees in bright sunshine may give a romantic picture, but hidden from view, exciting processes take place here. And it’s not always fun and games for the bees.

One of the most important plants in the diet of dairy cows is alfalfa (Medicago sativa). This protein-rich plant is the basis for almost all feed for the dairy farm. The ingredients of the plant ensure an increased milk production and thus improve the milk yield. The cows love this plant both directly from the pasture and processed in the feed. The bees are also happy about the many purple flowers that keep their nectar ready in the alfalfa fields.

But what exactly is the problem with the whole thing? The flowers of the alfalfa have a very special property: In order to ensure reproduction, they don’t rely on pollen getting stuck in the bees‘ bristle dress by chance. These flowers make sure that every bee that nibbles on the precious nectar also carries a large load of pollen to the next flower. For this purpose, the plant has developed a mechanism that hurls a concentrated load of pollen at the head of the bees with great momentum. The bees are literally hit in the face by the flower.

The Landing of a pollinating insect on the keel of the flower releases the stamens which are normally hidden under the wings of the flowers. They fold down and slap a load of pollen on the pollinator’s heads before they fold back again to their normal protected position, where they remain hidden until the next victim flies around.

The honeybees don’t seem to be particularly thrilled about this spectacle. They learn very quickly that there are other ways to get the nectar here. After a few painful learning experiences, they collect the nectar sideways from the inside of the flower and thus avoid triggering the mechanism. For the flowers, however, there is no successful pollination. As a result, only 1% of the flowers are pollinated by bees.

Different species of bumblebee seem to have fewer problems with this spectacle. They are the main pollinators of alfalfa and are not impressed by the punch on their heads. Solitary leafcutter bees (Megachile rotundata) are also effective pollinators. This type of bee is the most actively used solitary bee in the world in agriculture. In order to ensure successful pollination of the large alfalfa cultivation areas, areas are deliberately chosen in which a large number of wild bumblebee species occur or a large number of leafcutter bees are artificially settled.

So the next time you enjoy ice cream, think about how many bees had to take a slap in the face.

Text: Fabian Kalis

Image source: Ivar Leidus, CC-BY-SA 4.0, <https://creativecommons.org/licenses/by-sa/4.0/deed.de>, via Wikimedia Commons, no changes were made to the image.