Honeybees Adjust Diet to Pollen's Nutritional Imbalance

Honeybees can detect when their food has an imbalanced ratio of essential nutrients and adjust their consumption accordingly. This behavior helps them avoid consuming excessive amounts of certain amino acids. Researchers at the University of Oxford led this new study.

The findings, published in *Current Biology*, also show that many types of pollen do not provide the ideal mix of essential amino acids for bees. Essential amino acids are protein building blocks that animals must obtain through their diet. This discovery could help inform strategies for supporting healthy pollinator populations.

Bees obtain most of their food from nectar and pollen. Nectar provides sugar, while pollen is their main protein source. Pollen is the male reproductive material of plants. Its nutritional composition is not primarily designed as a food reward for pollinators.

Researchers compared the essential amino acid composition of honeybee tissues with pollen from 99 UK flowering plant species. They also created artificial foods mimicking either pollen or honeybee tissue composition. Newly emerged worker honeybees were fed these diets in laboratory experiments. Most pollen samples did not closely match the essential amino acid composition of honeybee tissues.

Bees given food that resembled their own tissue composition consumed more and gained more body mass. They also chose a diet with a higher proportion of protein. The amino acid histidine, required in small amounts by bees, may play a role in appetite control. When histidine levels were high, bees reduced their overall food intake.

Honeybees also transform pollen into a more nutritionally balanced food for their larvae. Worker bees collect pollen and store it as “bee bread” inside the hive. Nurse bees consume this bee bread and process its nutrients into glandular secretions, such as royal jelly, which they feed to developing larvae. Bee bread and royal jelly provide a more balanced essential amino acid profile than individual pollen sources. This suggests that combining diverse pollen and processing it through nurse bees helps compensate for nutritional shortcomings.

Wild bees, including bumblebees and solitary bees, feed pollen directly to their offspring. They may face greater nutritional challenges in habitats with limited plant diversity. Planting schemes for pollinators should focus on providing a diversity of pollen sources, not just a large number of flowers, to ensure bees receive a balanced diet.