LEXINGTON, Ky. – A recently released University of Kentucky study has found winter annuals can help save honey bees, which have been on the decline in the Bluegrass State.

Based on work supported by the USDA’s National Institute of Food and Agriculture and published in ‘Agriculture, Ecosystems and Environment,’ the researchers’ focus was on a critical time for honey bees: the late-winter and early-spring periods when honey bee colonies come out of their winter dormancy, and need for adequate nutrition is peaking.

According to Clare Rittschof, University of Kentucky associate professor of entomology, the hypothesis centered on winter annuals, plants often disregarded as mere weeds in fallow crop fields. The team found these could be an untapped resource, providing essential nutrition to honey bees during this vulnerable period.

To test this hypothesis, the researchers established honey bee colonies near various fields, some abundant with winter annuals, and others devoid.  

“Winter annuals, commonly dismissed as weeds, are actually a treasure trove of nutrition for honey bees during the critical late-winter and early-spring period,” Rittschof said. “This time is vital for the health and growth of bee colonies.”

Winter annuals are small plants that have an annual life cycle where they germinate, grow, and bloom in the late-fall, winter, and early-spring months, Rittschof told Farm World.

“People are probably most familiar with the deadnettles (which have a square stem and the flowers are reddish purple),” she said. “They carpet fields with purple flowers in March and April in the Midwest and Mid-South. Other common species are chickweeds, speedwells, and field pansies. There are a lot of species.

“We identified over 25 species of plants in our study that range in abundance,” she added. “Some of these are definitely bee-attractive (i.e., the deadnettles). However, for most, we don’t know much about the quality or quantity of nutrition they provide to various bee species.”

She said many bees – including honey bees – are generalist foragers, meaning they eat pollen and nectar from many types of flowers.

“So, it is likely that many of these flowers provide some food for bees,” she said. “Future work will have to verify this, though.”

She also told Farm World she talked with some beekeepers and other honey bee researchers about the feasibility of using winter annuals as good honey bee forage.

“Many beekeepers are already aware of these flowers and their contribution to honey bee nutrition,” she said. “However, other beekeepers do not realize that agricultural lands, including fallow crop fields, can provide good nutrition for honey bees. There has been a lot more focus on developing native wildflower plantings in natural areas.

“However, croplands grow a lot of weedy flowers that honey bees love, and in some cases, croplands have more flowers for honey bees than natural areas,” she added. “There are other considerations for keeping colonies near croplands, however, like pesticide exposure.”

But, she said, the benefits of nutrition may outweigh those costs in many locations.

“Some of the sites we used in this research were lands owned by beekeepers,” she said. “They were interested in supporting this research, and so they volunteered access to their properties.”

When asked how farmers can incorporate winter annuals without damaging later crops,” she said, “The cool thing about these plants is that they are naturally abundant but don’t seem to have many costs to growers. In fact, some researchers are developing flowering winter annuals as cover crop options in some farming systems.

“We are trying to encourage researchers focused on developing weed control practices to incorporate bee and pollinator nutrition into their efforts,” she added. “But generally, allowing these weeds to grow is a standard practice in many areas of the Midwest and Mid-South. Growers are already allowing these plants to grow and bloom.”

In other areas where there is heavy tillage or fall herbicide usage, she said, “These plants are eliminated, but to my knowledge, no one has assessed whether those growers have greater yields or weed control for problematic species. Many of the problematic species are summer annuals, which have a different life cycle.”

She said farmers can play a pivotal role in supporting honey bee populations by allowing winter annuals to grow in their fallow fields during winter. This practice supports the conservation of bees, contributing positively to soil health, and erosion control.

She said the methodology for the study involved close measures of colony growth, health, and productivity. She studied key factors such as colony size, honey quantity, and immune-system strength. The team also conducted an in-depth field analysis of the winter annuals, and aimed to quantify the plant abundance in predicting colony growth.

She said the results were both revealing and encouraging: “The honey bee colonies, positioned near fields rich in winter annuals, displayed more robust growth and stronger immune responses than those near fields lacking these plants.

“This finding was a significant indicator of winter annuals’ positive impact on honey bee colonies,” she added. “Winter annuals’ presence in fallow croplands significantly boosted honey bee colonies’ growth and immune response. It’s a clear indication that what we consider weeds can actually be beneficial for these crucial pollinators.”

While offering valuable insights, she said the study also opens up avenues for further research. 

“There’s still much to explore,” she said. “We need to delve deeper into which winter annuals are most beneficial for bees, and how we can incorporate the growth of these plants into modern farming practices without affecting crop yield.

“It’s an exciting and crucial field of study that has the potential in reshaping our agricultural landscape,” she added.