Four nutrients in flower pollens improve honey bee gut health

For the first time, four nutritional compounds found in different flowers have been directly proven to improve honey bee gut health, strengthen their immune systems and increase their lifespan, according to a study by scientists from the Agricultural Research Department of the US Department of Agriculture.

“We found that feeding caffeine, kaempferol, p-coumaric acid, or gallic acid – all nutritional compounds found in the nectar and pollen of various flowers – improved the abundance and diversity of bacteria in the gut. bees, ”entomologist Arathi Seshadri explained. She is with the ARS Invasive Species and Pollinator Health Research Unit in Davis, California.

Seshadri chose these four nutrients for testing because they are naturally present in honey bee’s favorite flowers, and have already been shown to improve honey bee lifespan and tolerance to a common pathogen, Nosema ceranae. Caffeine, for example, has also been shown by researchers to help bees learn better and improve their memory of the quality of floral scents and nectar. This study is the next step to further define how certain nutrients in flower pollen can help bees by showing a connection by improving the gut microbiome.

The gut microbiome is the total amount and species of all microorganisms and all of their collective genetic material present in the gut.

“The beneficial impact of these nutrients, found in a wide variety of flowers, has implications for healthier hive management through the design of better dietary supplements. It also highlights the need for flowering habitats that can provide bees with access to a rich diversity of pollen and nectar sources, ”Seshadri said.

Although the mechanism is not known to explain how these four nutrients improve the gut microbiome of honey bees, other researchers have suggested that p-coumaric acid alters the diversity of the gut microbiome by increasing the activity of immune genes in honey bees. honey bees. This disrupts the growth of pathogens acquired during foraging.

Examples of floral sources for these nutrients: caffeine: citrus fruits and coffee; gallic acid: mint, raspberry, sunflower and apples; kaempferol: petunias, asters, canola and poppies; and p-coumaric acid: buckwheat, roses and clover.

While caffeine had the greatest impact, all four nutrients resulted in an increase in the abundance of Commensalibacter, Snodgrassella, and Bombella bacteria, all of which are considered essential bacteria for a healthy bee gut.

Changes in the honey bee microbiome were seen immediately, just three days after receiving the supplements.

The growth spurt in the gut microbiome reached a plateau six days after supplementing the diet with each of the floral nutrients, and levels were reset to the original baseline levels when the supplements were discontinued.

“This rapid response shows how manipulating honey bees’ diets can impact their microbiome and reiterates the need for various flowering plants that can provide bees with easy access to these nutrients,” Seshadri said.

The study was published in the Journal of Applied Microbiology.