May 17 (UPI) -- When fed probiotics, bee colonies are more resistant to nosemosis, a fungal infection linked with colony collapse disorder.
Nosemosis, or nosema disease, is caused by a single-celled fungus called Nosema ceranae. When bees ingest the fungus with their food, the fungal cells can colonize the insect's intestinal walls.
"Under normal conditions, this fungus does not cause any problems for bees," Nicolas Derome, a professor of science and engineering at Laval University in France, said in a news release. "But when bees are subjected to stress, the microorganism can evade their immune system, causing an infection that can impair their ability to forage, hinder larval care, disturb the bees' orientation, and increase mortality."
A wealth of research suggests it is rarely a single factor that explains a decline in bee health. Instead, several stressors combine to increase mortality rates. Still, studies have revealed a correlation between nosemosis and colony collapse disorder, the crisis causing the decline of honey bee populations all over the world.
In a new study, researchers found probiotics can help prevent and treat nosemosis.
In lab experiments, Derome and his colleagues fed groups of bees four different types of probiotics. The probiotics were added to bees' food, a sugar syrup. Two types were commercial products added to feed on pork, chicken, shrimp and salmon farms. The other two were extracted from the guts of healthy bees.
All four probiotics worked equally well, decreasing the mortality rates of bees exposed to Nosema ceranae by 20 to 40 percent compared to a control group.
"Our results suggest that bacteria in the microbiota of bees can be as effective as commercial probiotics in treating nosemosis," said Derome. "It's important to note that given a very high infection rate, the probiotics tested did not reduce the number of fungi present in bees, but they allowed the bees to better tolerate them."
Derome and his colleague published the results of their research in the journal Frontiers in Ecology and Evolution.
Previous studies suggest both monoculture farming, leading to a less diverse diet, and exposure to pesticides can diminish the health of bees' microbiome, leaving them more vulnerable to parasites and disease.
Researchers are working to develop a variety of probiotic strains to combat disease.
"However, the real solution to this disease is to identify and correct the sources of stress disrupting the bees," Derome said.
Earlier this year, the European Union's policy makers agreed to ban three neonicotinoid insecticides blamed for bee decline.