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 today in the journal Nature .
One of the Oxford Bee Lab's hives. Credit: Caroline Wood.The challenge: addressing a critical nutrient deficiency
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 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-month period, 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.
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 substitute for pollen.
Senior author Professor Geraldine Wright , Department of Biology, University of Oxford
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."
From pollen to precision nutrition: Identifying and producing key bee sterols
Before this work, it was unclear which of the diverse sterols in pollen were critical for bee health. To answer this, the researchers chemically assessed the sterol composition of tissue samples harvested from pupae and adult bees. This required some extraordinarily delicate work; for instance, dissecting individual nurse bees to separate the guts. The analysis identified six sterol compounds that consistently made up the majority in bee tissues: 24-methylenecholesterol, campesterol, isofucosterol, β-sitosterol, cholesterol, and desmosterol.
Using CRISPR-Cas9 gene editing, the researchers then engineered the yeast Yarrowia lipolytica to produce these sterols in a sustainable and affordable way. Y. lipolytica was selected since this yeast has a high lipid content, has been demonstrated as food-safe, and is already used to supplement aquaculture feeds. To produce the sterol-enriched supplement, engineered yeast biomass was cultured in bioreactors, harvested, then dried into a powder.
Left: Jennifer Chennells weighing honeybee dietary choice tubes, Oxford Bee Lab. Right: Worker honeybees feeding in the lab, Oxford Bee Lab. Credit: Caroline Wood.Benefits for agriculture and biodiversity
Pollinators like honeybees contribute to the production of over 70% of leading global crops. Severe declines - caused by a combination of nutrient deficiencies, climate change, mite infestations, viral diseases, and pesticide exposure - poses a significant threat to food security and biodiversity. For instance, over the past decade, annual commercial honey bee colony losses in the U.S have typically ranged between 40 and 50%, and could reach 60 to 70% in 2025 . This new engineered supplement offers a practical means to enhance colony resilience without further depleting natural floral resources. Since the yeast biomass also contains beneficial proteins and lipids, it could potentially be expanded into a comprehensive bee feed.
Honey bees are critically important pollinators for the production of crops such as almonds, apples, and cherries and so are present in some crop locations in very large numbers, which can put pressure on limited wildflowers. Our engineered supplement could therefore benefit wild bee species by reducing competition for limited pollen supplies.
Co-author Professor Phil Stevenson , RBG Kew and University of Greenwich
Danielle Downey (Executive Director of honeybee research nonprofit Project Apis m. , not affiliated with the study) said: "We rely on honey bees to pollinate one in three bites of our food, yet bees face many stressors. Good nutrition is one way to improve their resilience to these threats, and in landscapes with dwindling natural forage for bees, a more complete diet supplement could be a game changer. This breakthrough discovery of key phytonutrients that, when included in feed supplements, allow sustained honey bee brood rearing has immense potential to improve outcomes for colony survival, and in turn the beekeeping businesses we rely on for our food production."
Next steps and future applications
Whilst these initial results are promising, further large-scale field trials are needed to assess long-term impacts on colony health and pollination efficacy. Potentially, the supplement could be available to farmers within two years.
This new technology could also be used to develop dietary supplements for other pollinators or farmed insects, opening new avenues for sustainable agriculture.
The study 'Engineered yeast provide rare but essential pollen sterols for honeybees' has been published in Nature .
