Engineered Yeast May Help Reverse Honeybee Declines

A team of scientists led by the University of Oxford, with support from the Royal Botanic Gardens Kew, University of Greenwich and the Technical University of Denmark, has developed a novel feed supplement that may help counteract colony declines in honeybees by improving their reproductive success. Their findings were published in Nature on August 20.

Tackling a nutritional imbalance in bee diets

Modern agricultural landscapes and climate change have reduced the floral diversity on which honeybees rely, resulting in a scarcity of essential nutrients found in pollen. Pollen contains sterols, lipid compounds that are vital to bee development. Many commercial supplements used by beekeepers are protein-rich but lack the sterol profile found in natural pollen, potentially leaving colonies undernourished.

“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."

Dr. Elynor Moore.

To address this, the researchers engineered the yeast Yarrowia lipolytica to biosynthesize six key sterols found in natural pollen. These sterols were incorporated into artificial diets and tested in feeding trials within enclosed glasshouses, ensuring that bees had access only to the experimental diets.

Colony-level improvements observed

After 3 months, colonies fed with the sterol-enhanced diet produced significantly more larvae that reached the viable pupal stage, up to 15 times more than colonies fed with sterol-deficient control diets. These colonies were also more likely to continue brood production through the duration of the trial. Larvae from supplemented colonies showed sterol profiles that matched those from bees foraging naturally, suggesting selective transfer of essential sterols from nurse bees to offspring.

Identifying and reproducing essential sterols

The researchers began by chemically analyzing sterol content in the tissues of pupae and adult bees. Dissections of nurse bees helped isolate gut samples for analysis. This identified six core sterols as consistent features of bee biology: 24-methylenecholesterol, campesterol, isofucosterol, β-sitosterol, cholesterol and desmosterol.

Using CRISPR-Cas9 gene editing, the team engineered Y. lipolytica to express the relevant biosynthetic pathways. This yeast was selected due to its food safety profile, high lipid content and commercial use in aquaculture feeds. The modified yeast was grown in bioreactors, harvested, and processed into powder for use in bee diets.

Broader implications for pollinator nutrition

The sterol-enriched feed may help reduce competition for floral resources between managed and wild pollinators. Since the yeast biomass also includes beneficial proteins and fats, it could be developed into a comprehensive nutritional supplement for honeybees. The technology may also be adapted for use in other managed pollinators or farmed insects, although further trials are required.

“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."

Danielle Downey.

According to existing data, commercial honeybee colony losses in the United States have hovered around 40% to 50% annually in the past decade and may exceed 60% in 2025. Improving diet quality could be a scalable strategy to support colony resilience.

Looking ahead

While the current findings are limited to controlled glasshouse conditions, the team plans to conduct field studies to determine the long-term effects of the supplement on bee health and pollination. Commercial availability of the feed could occur within two years, depending on regulatory approval and manufacturing scale-up.

Reference: Moore E, de Sousa RT, Felsinger S, et al. Engineered yeast provides rare but essential pollen sterols for honeybees. Nature. 2025. doi: 10.1038/s41586-025-09431-y

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