Honeybee nutrition might be key to healthy populations

A newly funded Texas A&M AgriLife Research project seeks to slow population losses among more than 2.6 million managed honeybee colonies in the U.S.

Honeybees provide pollination services that uphold $16 billion in U.S. agricultural crops. However, managed colonies have seen annual declines. Those include a 40% decline as recently as 2018-2019, said Juliana Rangel, Ph.D, AgriLife Research honey bee scientist in the Department of Entomology, Bryan-College Station.

The declines are attributed to several general issues, including poor nutrition and susceptibility to pathogens and diseases, said Pierre Lau, AgriLife Research graduate assistant, and a Texas A&M University doctoral candidate in Rangel’s laboratory.

Lau is also the project leader. To prevent future managed colony losses, his team will look for ways to strengthen bee colony immunity to disease pathogens by feeding them more nutritious diets.

The project is supported by a U.S. Department of Agriculture pre-doctoral fellowship  titled “Optimizing Macronutrient Contents in the Honeybee Diet as a Mechanism for Pathogen Defense.”

The research team includes Lau, Texas A&M graduate student Alexandria Payne, undergraduate students Cora Garcia and Jordan Gomez, along with Rangel. Spencer Behmer, Ph.D., AgriLife Research professor in the Texas A&M department of entomology, is also part of the team, as is his postdoctoral research associate Pierre Lesne, Ph.D.

Focusing on macronutrients

Researchers will place heavy focus on macronutrients, which are those nutrients in the highest demand by a healthy body for proper metabolism and physiology, Lau said.

His team’s work will be to first understand the varying amounts of proteins and lipids, or macronutrient ratios, present in bees’ diets. They will work to optimize an ideal diet with varying ratios of macronutrients, then they will observe physiological benefits to bees that receive increasingly nutritious dietary mixes. Commercial honeybee colonies succumb especially to Nosema ceranae and deformed wing virus. Nosema ceranae, a fungal pathogen, causes a fatal intestinal disease, while deformed wing virus causes death due to developmental complications in heavily infected adults, particularly due to crumpled wings.

Besides pathogens and diseases, Lau said, honey bee declines within agroecosystems – which describe most agricultural crop scenarios – can also come from parasitization, poor queen health, pesticide exposure and landscape fragmentation.

As such, in addition to immunity, the researchers will investigate how nutritional changes affect expression of genes that mediate proper honeybee development and growth.

Honeybee nutrition likely lacking

“We know that pollen is the most important source of nourishment for bees, but as a field of research, we have a poor understanding of all the macronutrients that make up pollen,” Lau said.

At the same time, Lau and collaborators, in an unpublished study, were able to determine the nutritional content of certain pollens. In the same study, they noted that honeybees preferred pollen with a lower ratio of protein to lipids, or P:L ratio, than what would be currently available in the beekeeping industry. Moreover, Lau said, existing research shows that organisms naturally seek out pathogen-fighting nutrients in their surroundings.

“Does this mean that honey bees can alter their macronutrient intake to self-medicate and increase their tolerance to a pathogen, given the availability?” Lau said. “It could also be that the role of lipids is more significant than we understand.”

Additionally, Rangel said, honeybees need certain plants in the vicinity to help them with physiological processes. Those include metabolizing certain macro and micronutrients. What if those plants are not available in a crop system?

“We know that honeybees need variety in their diet,” Rangel said. “But, to what extent are certain nutrients required, or even sought after, by the bees for proper nourishment?”

“Can we introduce supplemental macronutrients that allow honeybees to self-medicate in the presence of pathogen infections?” Lau added. “This will be our focus for the next two years.”

Read more about the Texas A&M Honey Bee Research Program online, and follow Rangel’s lab on Facebook.