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Bees are making less honey, and five decades of data reveals why

Honey production in the United States has experienced a noticeable decline since the 1990s, a trend that has puzzled both honey producers and scientists. 

A new study conducted by researchers at Penn State University has shed light on this mystery, revealing key insights drawn from an extensive analysis of data spanning five decades.

Focus of the study 

The researchers used a wealth of data sources, including those maintained by the United States Department of Agriculture (USDA) National Agricultural Statistics Service and USDA Farm Service Agency. 

The team meticulously examined a range of variables, such as average honey yield per colony, land use patterns, herbicide application, climatic conditions, weather anomalies, and soil productivity across the continental U.S.

Multiple contributing factors

The analysis revealed a complex interplay of factors impacting honey yields. Notably, the study highlighted the significant influence of land use changes, including the reduction of land conservation programs that are crucial for pollinators, and the widespread application of herbicides. These factors, along with varying annual weather patterns, were linked to fluctuations in honey production.

The role of soil productivity emerged as a particularly important factor. The study found that both warmer and cooler regions in the U.S. reported higher honey yields when their soils were more productive. This underscores the significance of soil’s physical, chemical, and biological properties in supporting not only crop growth but also the floral resources vital for honey bees.

Growing impact of climate

Study lead author Gabriela Quinlan, an NSF postdoctoral fellow at Penn State’s Department of Entomology and Center for Pollinator Research, said she was inspired to conduct the study after attending beekeeper meetings and conferences and repeatedly hearing the same comment: “You just can’t make honey like you used to.”

Quinlan’s analysis revealed an increasing correlation between climate and honey yields post-1992, indicating the growing impact of climate change on honey production.

“It’s unclear how climate change will continue to affect honey production, but our findings may help to predict these changes,” said Quinlan. “For example, pollinator resources may decline in the Great Plains as the climate warms and becomes more moderate, while resources may increase in the mid-Atlantic as conditions become hotter.”

Extensive data analysis 

Study co-author Professor Christina Grozinger said that while scientists previously knew that many factors influence flowering plant abundance and flower production, prior studies were conducted in only one region of the U.S.

“What’s really unique about this study is that we were able to take advantage of 50 years of data from across the continental U.S.,” said Professor Grozinger. “This allowed us to really investigate the role of soil, eco-regional climate conditions, annual weather variation, land use and land management practices on the availability of nectar for honey bees and other pollinators.”

Flower availability

The study also sheds light on the critical issue of floral resource availability. Different regions support diverse flowering plants based on their unique climate and soil characteristics. Identifying areas with abundant flowers is becoming increasingly important for creating bee-friendly landscapes. 

“A lot of factors affect honey production, but a main one is the availability of flowers,” said Quinlan. “Honey bees are really good foragers, collecting nectar from a variety of flowering plants and turning that nectar into honey. I was curious that if beekeepers are seeing less honey, does that mean there are fewer floral resources available to pollinators overall? And if so, what environmental factors were causing this change?”

Valuable new insights 

The investigation into the decline of honey production led to an exciting discovery about the importance of soil productivity, a relatively underexplored factor in determining the suitability of landscapes for pollinators.

Furthermore, the researchers found that changes in land use, such as decreases in soybean land and increases in Conservation Reserve Program land, positively impacted honey yields. The application rates of herbicides also played a crucial role, as eliminating flowering weeds can deprive bees of essential nutritional sources.

“Our findings provide valuable insights that can be applied to improve models and design experiments to enable beekeepers to predict honey yields, growers to understand pollination services, and land managers to support plant–pollinator communities and ecosystem services,” concluded Quinlan.

The study is published in the journal Environmental Research Letters.

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