Oxford Research Reveals Bees’ Ability to Regulate Intake Based on Amino Acid Balance

New research from the University of Oxford has identified a remarkable feeding behavior in bees: they can adjust their food consumption according to the balance of essential amino acids in their diet. This ability may help prevent the intake of excessive amounts of certain amino acids when pollen lacks the appropriate nutritional blend.

The study, published in Current Biology, highlights that many pollen types do not supply essential amino acids in proportions that align with the nutritional requirements of bees. Essential amino acids are critical building blocks of protein that bees cannot synthesize independently and must obtain through their diet. These findings could provide valuable insights for farmers, landowners, conservationists, and gardeners aiming to support robust pollinator populations.

The Nutritional Role of Pollen

Bees primarily rely on flower nectar and pollen for sustenance, with nectar serving as their main sugar source and pollen as their primary protein source. However, pollen evolved as the male reproductive element of plants, which means its nutritional content is not specifically designed to fulfill the dietary needs of pollinators such as bees.

To examine this discrepancy, researchers analyzed the essential amino acid profiles of honeybee tissues against pollen collected from 99 flowering plant species across the UK. They also developed artificial diets designed to reflect either the amino acid composition of various pollens or that of honeybee tissues. Newly emerged worker bees were tested with these diets under controlled laboratory conditions.

The analysis revealed that most pollen samples poorly matched the essential amino acid profiles found in honeybee tissues. Bees fed diets resembling their tissue composition consumed more food, gained greater body mass, and opted for a diet higher in protein.

Histidine’s Role in Food Intake Regulation

Researchers proposed that the amino acid histidine could significantly influence bees’ feeding behavior. Although it is essential, bees require histidine in relatively modest amounts.

To delve deeper, artificial diets varied in their histidine and branched-chain amino acids (like leucine and isoleucine) content were created. When histidine levels were elevated, bees reduced their overall food consumption, including both protein and carbohydrate intake. This phenomenon might stem from a post-digestive feedback mechanism that limits the intake of potentially harmful amino acids. Similar dietary regulation has been noted in other species, such as rats, where excess histidine converts to histamine, impacting food consumption controls.

Professor Geraldine Wright, the lead author from the Department of Biology at the University of Oxford, commented, “Although pollen is often assumed to be a near-perfect food for bees, it is the male gamete of plants and, unlike nectar, it is rarely produced solely as a reward for pollinators. This creates a conflict of interest between the plant and the pollinator.”

Nutritional Strategies for Honeybee Larvae

Honeybees also appear to adapt to the limitations of pollen when nurturing their larvae. Worker bees collect pollen from various flowers, storing it in the hive as ‘bee bread.’ Nurse bees consume this material, converting its nutrients into glandular secretions like royal jelly, which they then feed to developing larvae.

The study found that bee bread contains a more balanced amino acid profile than most individual pollen sources, with royal jelly matching honeybee tissue composition even more closely. These findings suggest that combining various pollen types and processing them through nurse bees allows honeybee colonies to offset the nutritional deficits of any single pollen source.

Professor Wright added, “We predict that honeybees have evolved to create glandular secretions that are the perfect food for their larvae, delivering the essential amino acid ratios that promote optimal growth.”

The Challenges for Wild Bees

In contrast, many wild bee species, including bumblebees and solitary bees, directly provide pollen to their offspring. These species may face greater challenges in habitats where flowering plant variety is limited, making it difficult to procure the necessary balance of essential amino acids for themselves and their young.

The study suggests that effective pollinator-friendly planting strategies should prioritize not only the quantity of flowers but also their nutritional quality and diversity. Professor Wright emphasized, “Our results suggest that planting for pollinators should not only focus on providing flowers throughout the season, but also on ensuring a diversity of pollen sources. A varied diet may be essential for bees to obtain the right balance of nutrients.”

This research involved collaboration with scientists from the University of Southampton, Lancaster University, Newcastle University, and The Hebrew University of Jerusalem.