The research team succeeded in engineering the yeast Yarrowia lipolytica to produce a precise mixture of six key sterols that bees need

A new study led by the University of Oxford could provide a cost-effective and sustainable solution to help tackle the devastating decline in honeybees. An engineered food supplement, designed to provide essential compounds found in plant pollen, was found to significantly enhance colony reproduction. The results have been published in the journal Nature.

Climate change and agricultural intensification have increasingly deprived honeybees of the floral diversity they need to thrive. Pollen, the major component of their diet, contains specific lipids called sterols necessary for their development. Increasingly, beekeepers are feeding artificial pollen substitutes to their bees due to insufficient natural pollen. However, these commercial supplements – made of protein flour, sugars, and oils – lack the right sterol compounds, making them nutritionally incomplete.

In the new study, carried out in collaboration with Royal Botanic Gardens Kew, University of Greenwich, and the Technical University of Denmark, the research team succeeded in engineering the yeast Yarrowia lipolytica to produce a precise mixture of six key sterols that bees need. This was then incorporated into diets fed to bee colonies during three-month feeding trials. These took place in enclosed glasshouses to ensure the bees were only fed on the treatment diets.

Key findings:

By the end of the study period, colonies fed with the sterol-enriched yeast had reared up to 15 times more larvae to the viable pupal stage, compared with colonies fed control diets.

Colonies fed with the enriched diet were more likely to continue rearing brood up to the end of the three months, whereas colonies on sterol-deficient diets ceased brood production after 90 days.

Notably, the sterol profile of larvae in colonies fed the engineered yeast matched that found in naturally foraged colonies, suggesting that bees selectively transfer only the most biologically important sterols to their young.

Lead author Dr Elynor Moore (Department of Biology, University of Oxford at the time of the study, now Delft University of Technology) added: “For bees, the difference between the sterol-enriched diet and conventional bee feeds would be comparable to the difference for humans between eating balanced, nutritionally complete meals and eating meals missing essential nutrients like essential fatty acids. Using precision fermentation, we are now able to provide bees with a tailor-made feed that is nutritionally complete at the molecular level.”

Our study demonstrates how we can harness synthetic biology to solve real-world ecological challenges. Most of the pollen sterols used by bees are not available naturally in quantities that could be harvested on a commercial scale, making it otherwise impossible to create a nutritionally complete feed that is a pollen substitute, said Senior author Professor Geraldine Wright, Department of Biology, University of Oxford