Indiana University researchers say they have identified a specific bacterial microbe that, when fed to honeybee larvae, can reduce the effects of nutritional stress on developing bees — one of the leading causes of honeybee decline.
Their paper entitled, Honey bee symbiote buffers larvae against feeding stress and replenishes lysinewas published in the International Society for Microbial Ecology Journal.
Because they will pollinate almost anything, honeybees are extremely useful for agriculture and play a huge role in food security. But concerns about their decline have persisted for decades, with one of the most extreme stressors being considered restricted nutrition.
Beekeepers in the United States reported losing 45.5 percent of their managed bee colonies between April 2020 and April 2021.
“The effects of poor nutrition are most damaging on the developing honey bee larvae, which grow into workers unable to meet the needs of their colony,” said Irene Newton, a professor in the IU’s Department of Biology. Bloomington College of Arts and Sciences. who led the investigation. “It is therefore essential that we better understand the nutritional landscape of honeybee larvae.”
Newton said honeybees need to collect pollen and nectar from various plants and flowers to keep their colonies healthy all year round. But many bees in the US lack this floral diversity — and she attributes that deficiency in part to large-scale agricultural fields.
“We’ve changed the way we use our land in the US,” Newton said. “Now we have tons of monoculture crops like maize, which are wind pollinated and therefore of no use to bees, covering acres and acres of land. Other crops pollinating bees are also grown in monoculture, limiting the options for bees.
“If you limit yourself to eating just one thing, it’s not healthy for you. You should have a broad diet that can meet all your nutritional needs. Bees are the same.”
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Honey bee larvae are fed by their sister bees. Their diet consists of ingested ingredients such as nectar and pollen, as well as royal jelly – a bee gland secretion that is complex and nutritious. If larvae are destined to become queens, they will eat royal jelly all their lives. If they are workers, their diet will shift to nectar and pollen after a few days.
Royal jelly is not only more nutritious than nectar and pollen, but has long been known to possess potent antimicrobial properties due to its acidity, viscosity and the presence of antimicrobial peptides. This means most microbes exposed to royal jelly die, Newton said.
According to their new study, Newton and her research team found that a specific microbe — Bombella apis – is the only larva-associated bacterium that can really thrive in royal jelly. They thought so too B. apis makes royal jelly more nutritious by significantly increasing its amino acid content, which helps develop bees to resist nutritional stress.
“We’ve identified a honeybee nutritional symbiote — a microbe that can help support the bees against food scarcity and stress,” Newton said. “When we restricted bee nutrition during development, we saw a decrease in mass for the bees; bees were much smaller than their control counterparts.
“When B. apis was added to the same bees, although they had poor nutrition, they achieved the same mass as control bees fed complete diets. The microbe was able to make up for the bad diet. This suggests that B. apis could be added to colonies as a probiotic to protect against nutritional stress.”
The results suggest that B. apis may have potential as an important adjunct to future beekeepers’ efforts to counteract the negative impact of poor nutrition on honeybee health. B. apis can survive in sugar water for more than 24 hours, so beekeepers who are already replenishing their colonies may be able to B. apis probiotics in their bees’ diets.