Better together

In the last few years, growers have witnessed two agricultural setbacks.

Bee populations in the United States are under extreme stress, potentially threatening the crops that need them to produce fruit. At the same time, a hopeful surge in growing industrial hemp — banned in this country since the 1930s, but revived in the 2018 Farm Bill as a possible high-value niche crop to boost small farmers’ bottom lines — has waned. 

But out of two setbacks may come one solution: Could hemp represent salvation for bees?

Recent work by CAES research professor Beatrice Dingha, Ph.D., suggests that pollen from industrial hemp provides nutritional benefits that bees need to thrive, and bees attracted to hemp can help increase yields of crops that depend on pollinators.

Dingha, who earned her doctorate in entomology from Auburn University, said bees are critical to food production in the United States.

“When we talk about bees, we’re talking about food security for us and the bees,” said Dingha, who has been on the faculty of the Department of Family and Consumer Sciences and the Department of Natural Resources and Environmental Design since 2010.

“Without bees, we might not find certain foods that depend on pollinators in the grocery store. And if plants are not able to provide bees with the pollen and nectar they need, then the health and survival of bees are threatened.”

There’s no denying it: Bees are in trouble. The U.S. Department of Agriculture estimates that managed honey bee colonies in the United States number about half what they were in the 1940s. To keep bee populations constant, commercial beekeepers must replace roughly a third of their hives each year. Populations of wild bees have declined as well. By some estimates, more than 40% of the wild bee species native to the U.S. are at risk of extinction. 

Wild and domesticated bees face similar perils: arthropod pests, pesticides, pathogens and habitat loss due to development and climate change. These hazards represent a profound threat to American agriculture because roughly a third of the food we eat — almonds, apples, melons, pumpkins, squash, strawberries, watermelon and many other nuts, fruits and vegetables — depends on pollinators such as bees. 

Dingha saw research opportunities with the return of industrial hemp when Congress legalized commercial growing of hemp in this country in 2018. When she and her colleagues surveyed organic farmers across North Carolina, they discovered significant interest in growing hemp.

Dingha in 2019 was awarded a USDA Sustainable Agriculture Research and Education grant of nearly $230,000 over three years to support a project designed to develop a sustainable cropping system for industrial hemp production.

For her first objective, Dingha measured bee activity and chemical composition of pollen on four varieties of industrial hemp (Cannabis sativa L.) grown on the N.C. A&T University Farm. Not only did the hemp plants attract significant bee activity, these pollinators also showed high preference for the Joey variety. The results of this research were published this summer in the journal Insects.

It’s unclear why bees showed such preference. But Dingha came away from the project with a conviction: “At the end of the day,” she said, “hemp is a crop that will contribute to food security and enhance bee health.”

Next, Dingha turned to intercropping, the practice of simultaneously planting two or more crops in close proximity — that is, in rows, strips or even adjacent fields. For this objective, Dingha intercropped three plants: the Joey variety of industrial hemp, cowpeas (a legume better known as black-eyed peas) and squash, a pollinator-dependent plant. The pollen produced by hemp and the nectar generated by cowpeas attracted an abundance of bees, which led to a higher-than-normal increase in the squash yield.

Those findings, which Dingha is currently writing for publication, are important in at least two ways. They reinforce earlier research that suggests that intercropping can attract more pollinators and increase crop yields. And they give farmers a new reason to grow hemp.

Once industrial hemp became legal, there was a rush to plant a potentially high-value crop that produced fiber, oilseed and cannabidiol, better known as CBD, which some believe has health benefits. But Dingha noted that hemp is a delicate plant that by law must be destroyed if its tetrahydrocannabinol, or THC, content exceeds 0.3%. (THC is the compound responsible for the high associated with marijuana.) 

Because the demand for hemp was less than U.S. growers anticipated and the regulatory environment around CBD products remains uncertain, farmers have largely turned away from hemp. According to the USDA, U.S. hemp acreage in 2022 had fallen by nearly 50% from the previous year while the value of hemp production dropped by more than 70%. 

Dingha has this message for growers: Don’t give up on hemp. Bees and other pollinators need hemp pollen, and intercropping can help growers see a bigger return on their investment.

“Growers should still have hope because hemp can be a very lucrative crop,” Dingha said. “Other countries are doing well with hemp. Why can’t we?”