The Missing Nutrient in Pollen Substitutes – And How Engineered Yeast Could Fix It

If you keep bees in New Zealand, you already know the pain points: long dearth periods, monoculture landscapes, declining forage diversity, and the rising cost of pollen supplements that still do not perform like real pollen. A new 2025 Nature study has identified exactly what is missing from current supplements—and has developed a breakthrough yeast-based solution that could eventually allow colonies to rear brood even when no pollen is available. This research has major implications for colony strength, overwintering success, and long-term hive health in New Zealand’s increasingly variable climate.

Summary of the Study

1. The Problem: Not All Pollen Substitutes Are Created Equal

Artificial pollen substitutes (soy flour, yeast, protein blends, etc.) have been used for over 40 years, but they lack critical sterols found in natural pollen. Honeybees cannot make their own sterols, they must get them from food. These sterols are required for:

• brood development

• hormone production

• cell membrane formation

• overall colony growth and resilience

Without these sterols, colonies can survive but cannot sustain proper brood rearing.

2. The Key Sterol Bees Need Most

The study analysed honeybee tissues and found that nurse bees and brood depend heavily on 24-methylenecholesterol (24-MC) - making up 60–70% of sterols in bee pupae. Other required sterols include:

• isofucosterol

• campesterol

• cholesterol

• β-sitosterol

• desmosterol

Natural pollen contains these in varying amounts, but no commercial pollen substitute replicates this profile.

 Fig. 1 | Sterol nutrition of a honeybee colony. a, Adult worker honeybees collect and eat floral pollen, which provides proteins, lipids and micronutrients. Pollen foraged from flowers is packed into cells of the wax comb with honey to form bee bread. Nurse bees consume bee bread and create glandular secretions (jelly), which include sterols required for development, to larvae. Larvae develop into pupae and eventually emerge as female workers, queens or drones (males).

3. The Breakthrough: Engineering Yeast to Make Bee Sterols

Researchers genetically engineered the yeast Yarrowia lipolytica to produce a custom blend of the exact sterols bees rely on.They developed:

• a single-sterol strain (high 24-MC)

• a mixed-sterol strain (mimicking all key sterols found in pupae)

The mixed-sterol biomass was then incorporated into an artificial diet and fed to small colonies.

4. Feeding Trials: What Happened to the Bees?

Colonies were fed one of four diets:

1. Mixed-sterol yeast diet (new engineered strain)

2. Control yeast diet

3. Wild-type yeast diet

4. Base artificial diet with no sterols

All colonies had no access to pollen.

Results after 3 months:

• Colonies on the mixed-sterol diet reared significantly more brood, especially capped brood.

• Colonies on the sterol-free diets gradually lost the ability to rear brood—similar to pollen starvation.

• Mixed-sterol colonies still had capped brood at the end of the trial when all others had almost none.

In short: Sterols were the make-or-break factor for brood production.

5. Why This Matters for NZ Beekeepers

New Zealand beekeepers face:

• long dearth periods in many regions

• wet springs or dry summers, reducing natural pollen supply

• increasing hive losses linked to nutrition stress

• the cost and inconsistency of pollen patties

This research shows that only specific sterols—not just protein—determine whether a colony can keep raising brood during pollen shortages.

If supplemented diets could reliably include these sterols, NZ beekeepers could see:

• stronger colonies heading into winter

• more consistent spring build-up

• better recovery after varroa treatments

• reduced competition with native pollinators

• more reliable queen raising and nuc production

  
  

6. What’s Next?

The yeast strain is not yet commercially available, but the science is now proven. The study suggests future supplements could:

• include sterol-rich yeast biomass

• avoid the need for expensive sterol extraction

• provide a complete pollen substitute (not just a partial one)

This could eventually reshape how NZ beekeepers feed colonies during tough periods.

Final Takeaway

For years, the industry has focused on protein content in pollen substitutes. This groundbreaking study shows that sterols—not protein—are the real limiting factor in brood production when pollen is scarce.If engineered-yeast sterols enter the commercial market, they could become the first truly effective full pollen replacement, giving NZ beekeepers a powerful tool against dearth, climate variability, and colony losses.

Paper: Engineered yeast provides rare but essential pollen sterols for honeybees (Nature, 2025) https://www.nature.com/articles/s41586-025-09431-y