Therapeutic Effect of Lachancea fermentati on Vairimorpha (Nosema) Ceranae Infection in Bees

Nosemosis is caused by microsporidian species, Vairimorpha ceranae (V. ceranae). V. ceranae-infected bees exhibit various such symptoms as digestive issues, weakened immunity, and shortened lifespans. We aimed to verify the therapeutic effects of Lachancea fermentati (L. fermentati) on V. ceranae-infected honeybees. Lachancea fermentati were isolated from the midgut and confirmed as L. fermentati using ribosomal DNA (rDNA) analysis. Whether the bees had fed on L. fermentati was confirmed using real-time polymerase chain reaction (PCR). To analyze the therapeutic effect of L. fermentati on V. ceranae infection, various concentrations of L. fermentati were fed to V. ceranae-infected bees, and DNA was extracted from the bees to evaluate V. ceranae gene expression levels. The therapeutic effect of L. fermentati against nosemosis was compared with that of fumagillin, which is commonly used to treat V. ceranae infection. Notably, V. ceranae-infected bees had undetectable V. ceranae gene expression after being fed L. fermentati (1×108 spores/mL). The therapeutic effect of L. fermentati against V. ceranae infection was comparable or even superior to that of fumagillin. These results indicate that L. fermentati has a potent therapeutic effect on nosemosis.