It is additionally used as an energy carrier. Honey bees rank among the most successful living beings in the world, having populated the earth for millions of years. They use not only carbohydrates but also proline, an amino acid with virtually the same energy content as sugar for purposes of energy production. Experiments by Karl Crailsheim from the Institute of Zoology at the University of Graz have shown that honey bees do not depend on the proline content in their food, since they are able to synthesise it themselves, if required. The investigations have also shown that the percentage of this amino acid is closely related to the age and task of the individual animal.
Drones have the highest proline level, followed by the queens and the workers.
Proline fulfils various tasks in the bee's body. On the other hand, proline can also be used as an energy source. The permanent supply with sugars and the high percentage of proline in the blood, combined with the ability to switch to this substitute energy source at any time, gives honey bees a strategic advantage in the search for food and in thermoregulation. In summer the produced energy is used as alternative 'fuel', while in winter the bees could use it to rapidly heat the hive, if required, and thus to guarantee the survival of the workers and the queen. The high energy reserves in the hive allow the bees to fly earlier, faster and further than their competitors.