Which Bees Work Harder? What Kiwi Beekeepers Can Learn from the Latest U.S. Bee Stock Study

If you’re a New Zealand beekeeper battling Varroa, juggling honey yields, or just curious about bee genetics, this study has your name on it. The latest U.S. research offers compelling data on how different bee stocks perform under pressure - and it may just reshape how you think about your next queen order.

There’s fresh buzz from across the Pacific, and it could help you make smarter choices for your hives here in Aotearoa. A major new study from the USDA’s Carl Hayden Bee Research Center has taken a deep dive into the performance of three honey bee stocks: Italian, Russian, and Pol-line (a mite-resistant line) using continuous hive monitoring over two seasons.

The results? Not all bees are created equal.

Russian bees

Productivity vs. Efficiency: It's Not What You Think

Italian bees produced more brood and had larger adult bee populations, but they also lost weight faster during nectar dearth and had higher mite levels. In other words, bigger doesn’t always mean better.

In contrast, Russian and Pol-line colonies gained weight faster during the honey flow and conserved their stores better in the off-season. That means potentially better yields and less feeding needed when the flowers dry up.

Varroa Counts: A Warning Sign for NZ?

Italian bees had three times the mite drop compared to the other two stocks. That matters. With miticide resistance rising in New Zealand, bee genetics may be our best next step in Varroa control. The Pol-line and Russian bees are bred for hygienic behavior, which helps suppress mite levels without chemicals.

Foraging and Flight Times

The study also looked at when bees started and ended their daily foraging. Pol-line bees started later but ended later too. Despite having fewer foragers, they gained weight at a similar rate to the Russian bees, suggesting quality, not just quantity, in foraging effort.

What About Temperatures and CO₂?

All colonies kept brood nest temperatures stable (around 35.5°C), but Pol-line hives had consistently higher CO₂ levels. That might indicate tighter clustering or different ventilation strategies, though the science here is still evolving.

Why It Matters to NZ Beekeepers

Our environment, flowering cycles, and Varroa pressures are different, but the principles apply. If you’re selecting for beneficial traits, raising queens, or just experimenting with bee lines, this research backs the case for resistant bees that manage resources well, not just the ones that look the busiest.

With breeding programs growing in New Zealand, including lines showing hygienic traits, this study is a timely reminder: choosing the right bees

can reduce your chemical use, improve colony resilience, and potentially give you better returns on your hard work.

Keen to Learn More?

Check out the full open-access study:Meikle et al. 2025, Apidologie