The benefit was clearest in cold conditions, and it grew stronger the more of the supplement the bees ate.
She studies honeybee physiology and wanted to know whether diet could help bees withstand temperature extremes.
Bees in the cold and heatAfter the three weeks, groups of bees faced one of four temperatures for up to ten days.
Researchers found that feeding honeybees probiotics and inulin improved survival in cold conditions while lowering oxidative stress across temperature treatments.
A simple dietary supplement can measurably improve honeybee survival through cold snaps, and the effect grows with the dose.
Feeding honeybees a daily dose of probiotics and a gut-friendly fiber helped them survive sharp swings in temperature, a new study has found. The benefit was clearest in cold conditions, and it grew stronger the more of the supplement the bees ate.
The finding suggests a cheap, simple way for beekeepers to help colonies cope with the erratic weather a warming climate keeps delivering.
There is a hard limit, though. Once the heat turned extreme, no dose could keep the bees alive.
Testing bee resilience
The work was led by Dr. Najmeh Sahebzadeh at the University of Zabol (UOZ) in southeastern Iran.
She studies honeybee physiology and wanted to know whether diet could help bees withstand temperature extremes. Her team raised newly emerged worker bees and fed them for three weeks.
In an email to Earth.com, Sahebzadeh said, “As a keystone species for crop pollination and, by extension, global food production, honeybees are particularly vulnerable to these fluctuations, making strategies that bolster their physiological resilience all the more valuable.”
The diet paired a commercial probiotic, a blend of gut bacteria, with inulin, a fiber drawn from chicory root that beneficial microbes feed on.
Working with a collaborator at the University of Alberta (UAlberta) in Canada, the researchers tested four strengths, up to ten grams of each per liter of syrup.
Bees in the cold and heat
After the three weeks, groups of bees faced one of four temperatures for up to ten days.
Two were cold, at 39°F (4°C) and 59°F (15°C), while one matched the hive’s comfortable 95°F (35°C) and the last hit a punishing 104°F (40°C).
Cold alone steadily killed the un-supplemented bees. The supplement pushed back, and the effect was substantial.
Benefits in the cold
At 39°F (4°C), the two highest doses kept more than 70% of bees alive across the ten days, while the unfed controls died off fastest.
Milder cold at 59°F (15°C) helped even more, with the strongest dose keeping more than 80% of bees alive. That fits a growing picture of the gut as a cold-weather ally.
One recent paper found that lactic-acid bacteria come to dominate the honeybee gut in winter, when colonies must survive months of cold. A steadier community of these microbes may be part of what carries bees through.
Heat overwhelms the bees
Heat told a different story. At 104°F (40°C), bees died fast no matter what they had eaten. The unsupplemented controls were essentially all dead within a day, and the richest dose bought only about three extra days before the same end arrived.
The reason is blunt. Extreme heat damages the machinery of life directly, cooking proteins and breaking apart cell membranes faster than any gut benefit can offset.
A healthier gut cannot rescue a bee whose basic biology is already failing. That limit is sobering, because heat is the threat bees increasingly face.
A large analysis of dozens of bumblebee species tied a rising count of extreme-heat days to local extinctions, as populations were pushed past the temperatures they could stand.
Shade and ventilation, not diet, remain the most effective protections against severe heat.
Researchers found that feeding honeybees probiotics and inulin improved survival in cold conditions while lowering oxidative stress across temperature treatments. Image credit: Najmeh Sahebzadeh and colleagues
Calmer internal defenses
The most surprising result came from inside the bees. Stress leaves a chemical trace.
When animals face it, their cells throw off reactive oxygen molecules that damage tissue, and they lean on antioxidant enzymes to clear the mess.
This build-up of damage is called oxidative stress, and its usual signature is a spike in those enzymes. The supplemented bees showed the opposite. Across every temperature, the more supplement they had eaten, the lower their antioxidant enzyme activity ran.
Under the worst heat, one key enzyme in the control bees reached roughly 3,000 units, and the top dose cut that by nearly half. That stability stood out to the researchers.
Speaking with Earth.com, Sahebzadeh said, “What stands out is that this protective effect was not confined to a single temperature extreme; it held up independently under both cold and heat stress, suggesting a level of consistency that isn’t tied to the specific nature of the thermal challenge involved.”
The gut connection
A lower reading sounds like a weaker defense, but the researchers read it the other way.
If the supplement stops damage from piling up in the first place, the bees never need to push their enzymes so hard. The quieter response, in this view, signals less stress rather than less protection.
The likely explanation sits in the gut microbiome, the community of bacteria that helps bees digest food and hold off disease.
The probiotic adds helpful microbes, while the inulin feeds them. Together, they may help bees extract more energy from food and neutralize damaging molecules.
No one profiled the bees’ bacteria directly in this experiment, so the gut connection stays a strong inference rather than a proven chain.
The same fiber-and-microbe pairing has proved useful before. An earlier study found it helped bees resist a common gut parasite and live longer.
A tool for beekeepers
The findings are narrow but useful. A simple dietary supplement can measurably improve honeybee survival through cold snaps, and the effect grows with the dose.
For beekeepers watching colonies struggle through unstable springs and harsh winters, that could provide a practical, low-cost tool for improving resilience.
Replying to Earth.com’s questions, Sahebzadeh said, “Taken together, this study introduces a workable and cost-effective model for the beekeeping industry, one that departs from conventional practice in a meaningful way.”
Testing real colonies
The study has real weight. It used young bees raised in the lab, which never picked up gut bacteria the natural way, from older nestmates, so whole colonies may behave differently.
Field trials in working hives are the obvious next test. Even with those caveats, the direction is clear.
As weather grows more erratic, the gut is emerging as a place where beekeepers might build resilience one feeding at a time, at least against the cold. But for now, protecting bees from extreme heat will depend largely on managing conditions outside the hive.
The study is published in PLOS One.
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