Balance is Key for Nurse Honey Bees’ Diets

ARS Research Ecologist/Entomologist Pierre Lau gathering nurse honeybees.

Honey bees are important agricultural pollinators, and their nutritional intake can greatly impact their livelihoods. ARS scientists are looking at honeybees’ nutritional preferences to develop better food sources for honeybees and protect colonies from possible losses. 

Current research on honeybees’ nutrition has mostly focused on protein-carbohydrate intake and regulation. However, little is known about their intake of proteins and lipids. Pollen provides bees with their primary source of proteins and lipids, but their amount or ratio can vary among plants that bees forage in nature. 

Lipids are part of a balanced diet for bees and are important for energy storage, cell membrane structure, hormonal production, and immune function. Bees obtain lipids from pollen, and pollen is necessary for rearing and developing bees.

To learn more about honey bees’ diets, ARS and Texas A&M University researchers observed how nurse bees, who are tasked with feeding developing larvae, regulate their protein-lipid intake in an experimental study using diets that mimicked the macronutrient content in pollen. 

The researchers used the Geometric Framework for Nutrition, a tool that helps researchers understand how multiple nutrients interact and affect an organism’s health and physiology, to assess their findings. 

“Our study shows that nurse bees favored diets containing 30% protein and 20% lipids,” said Pierre Lau, a research ecologist at the ARS Pollinator Health in Southern Crop Ecosystems Research Unit in Stoneville, MS. 

Lau added that nurse bees generally regulate this protein-to-lipid ratio when given a choice between imbalanced diets. According to Lau, this finding showed that bees, like humans, need a balance of proteins and lipids to maintain good health. 

Nurse honeybees feed on nutrients during a study. (Photo by Pierre Lau, ARS)

“Nurse honey bees stopped feeding once they hit their protein or lipid threshold,” said Lau. 

“This ‘strict restraint’ rule suggests that, for nurse bees, there is a cost of overeating protein and lipids. Too much of any nutrient can be harmful. Many insects have mechanisms and strategies to regulate their dietary intake for their fitness goals.” 

Lau and his collaborators plan to use these findings to better understand bee management, especially since poor nutrition can have detrimental effects on bee colonies. 

“Commercial beekeepers often rely on pollen substitutes to feed honeybees,” said Lau. 

Pollen substitutes include dry powders, sugar-based mixtures, and pre-made patties. These substitutes can consist of ingredients such as soy flour, brewer’s yeast, and microalgae. 

“These substitutes can be suboptimal compared to pollen and natural food sources that bees find from foraging on flowering plants,” said Lau. “Through a more detailed understanding of honey bees’ nutritional needs and their behavior, we can develop appropriate formulations to fulfill bee nutritional needs.” 

The study was published in iScience. – by Jessica Ryan, ARS Office of Communications

###