Managed honeybees might be masking a global pollination crisis

(CN) — Wild bees and other natural pollinators are disappearing around the world. But farmers may not have felt the full impact yet, largely because they’re bringing in honeybee hives.

Researchers — in a study published Monday in the Proceedings of the National Academy of Sciences — say that pollination-related crop yield shortfalls fell from roughly 73% before the 1980s to about 26% by the 2010s.

The research team, led by Catarina Siopa of the University of Freiburg and the University of Coimbra, analyzed 165 studies published between 1950 and 2019, spanning 86 crops grown across multiple continents. They compared crop yields under natural pollination with yields after researchers added supplemental pollen by hand, conducting 790 comparisons.

Across all crops and years, insufficient pollination was associated with an average yield loss of 36%. While those losses are large, they have declined steadily over time.

The team found one likely explanation: pollination management has gotten better. Farmers have improved how they deploy managed bees, usually honeybees, through smarter hive placement and healthier colonies.

“Current pollination management practices have become increasingly efficient in crop production systems, possibly helping to mitigate the negative impacts of wild pollinator declines,” the researchers wrote.

About 42% of the fields included in the analysis used managed pollinators. Of those, 68% relied on the common honeybee, known scientifically as Apis mellifera.

Fields with managed pollinators saw pollination-related yield losses steadily decline over time. Fields without them showed no similar improvement, with losses holding near 35%.

Researchers say the improvement was not because more farms started using managed pollinators. The share of farms using them stayed roughly the same over time.

Instead, researchers believe farmers got better at managing them. Healthier colonies, smarter hive placement and a growing understanding of how managed and wild pollinators work together may all have contributed.

Pollinators play a huge role in the global food supply. Bees and other animals pollinate roughly 75% of the world’s major crops, which account for about one-third of global food production.

But the scientists caution that improvement does not mean the loss of wild pollinators is no longer a concern.

“The stable (levels of pollination loss) under wild pollinator visitation should not be interpreted as evidence of absence of pollinator decline,” they wrote. “Rather, they suggest that, despite pollinator declines, the ecosystem service provided by pollinators is being maintained over time, most likely through compensatory mechanisms or functional resilience.”

In other words, pollination services appear to be holding steady in part because managed honeybees are compensating for losses among wild species. The question is how long that can last.

“Pollinator management still relies predominantly on a single species,” the researchers wrote. “This dependency poses significant risks to agricultural sustainability.”

The authors argue that protecting crop yields over the long term will require more than honeybees alone. That means preserving habitat for wild pollinators, expanding the use of other managed species such as bumblebees and solitary bees, and developing crop varieties that can partially pollinate themselves.

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