Why do bees produce less honey? Study reveals clues from five decades of data

Honey yields in the United States have been declining since the 1990s, with honey producers and scientists not sure why, but a new study by Penn State researchers has uncovered clues to the mystery of the missing honey .

Using five decades of data from across the United States, the researchers analyzed potential factors and mechanisms that could affect the number of flowers growing in different regions and, by extension, the amount of honey produced by bees.

The study, recently published in the journal Environmental Research Letters, found that changes in honey yields over time were linked to herbicide application and land use, such as a decrease in land conservation programs supporting pollinators. Annual climate anomalies also contributed to yield variations.

The data, taken from several open source databases, including those maintained by the National Agricultural Statistics Service and the USDA Farm Service Agency of the United States Department of Agriculture (USDA), included information such as average yield in honey per honey bee colony, land use, herbicide use. , climate, weather anomalies, and soil productivity in the continental United States.

Overall, the researchers found that climatic conditions and soil productivity – the ability of soil to support crops based on its physical, chemical and biological properties – were among the most important factors in estimating crop yields. Honey. States in warm and cool regions produced higher yields of honey when they had productive soils.

Ecoregional soil and climate conditions set baseline levels of honey production, while changes in land use, herbicide use and weather conditions influence the amount produced in a given year, summarized Researchers.

Gabriela Quinlan, lead author of the study and a National Science Foundation (NSF) postdoctoral researcher in the Department of Entomology and Pollinator Research Center at Penn State, said she was inspired to conduct the study after attending beekeeper meetings and conferences and repeatedly hearing the same comment: you can’t make honey like you used to.

According to Quinlan, climate became increasingly linked to honey yields in the data after 1992.

“It is unclear how climate change will continue to affect honey production, but our results could help predict these changes,” Quinlan said. “For example, pollinator resources could decrease in the Great Plains as the climate warms and becomes more moderate, while resources could increase in the Mid-Atlantic as conditions become warmer.”

Christina Grozinger, Publius Vergilius Maro professor of entomology and director of the Pollinator Research Center, co-author of the paper, said that although scientists previously knew that many factors influence the abundance of flowering plants and flower production, previous studies were conducted in only one region of the country. United States

“What’s really unique about this study is that we were able to take advantage of 50 years of data from across the continental United States,” she said. “This allowed us to really study the role of soil, ecoregional climate conditions, annual weather variations, land use and land management practices on nectar availability for honey bees and other pollinators. “

One of the biggest stressors for pollinators, researchers say, is a lack of flowers that provide enough pollen and nectar for food. Since different regions may support different flowering plants depending on climate and soil characteristics, they said there is growing interest in identifying regions and landscapes with enough flowers to make them bee-friendly. .

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

For Quinlan, one of the most interesting findings was the importance of soil productivity, which she says is an under-explored factor in analyzing the suitability of different landscapes for pollinators. While many studies have examined the importance of nutrients in soil, less work has been done on how soil characteristics such as temperature, texture, and structure (properties that help determine productivity) affect pollinator resources.

The researchers also found that decreasing soybean cropland and increasing Conservation Reserve Program land, a national conservation program that has been shown to support pollinators, both had positive effects on honey yields.

Herbicide application rates were also important in predicting honey yields, potentially because removing flowering weeds can reduce the nutritional sources available to bees.

“Our results provide valuable information 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 communities and pollinators and ecosystem services,” Quinlan said.

To learn more about land use, floral resources and weather in specific areas, visit the Beescape tool on the Center for Pollinator Research website.