Potential of Wormwood and Oak Bark-Based Supplement in Health Improvement of Nosema ceranae -Infected Honey Bees.

Nosema ceranae , a microsporidian parasite, as one of the stressors that contribute to honey bee decline, has a significant negative impact on the longevity, productivity, and reproductive capacity of honey bee colonies. There are several different strategies for Nosema infection control, including natural-based and antibiotic-based products. In this study, we tested wormwood and oak bark-based supplement "Medenko forte" on survival, Nosema infection, oxidative stress, and expression of immune-related genes in artificially N. ceranae -infected bees. The results revealed a positive influence on the survival of Nosema -infected bees, irrespectively of the moment of supplement application (day 1, day 3, or day 6 after bee emergence), as well as reduction of Nosema loads and, consequently, Nosema -induced oxidative stress. Supplementation had no negative effects on bee immunity, but better anti- Nosema than immune-stimulating effects were affirmed based on expression levels of abaecin, defensin, hymenoptaecin, apidaecin, and vitellogenin genes. In conclusion, the tested supplement "Medenko forte" has great potential in the health protection of Nosema -infected bees. However, further investigations need to be performed to elucidate its mechanisms of action.