Efficiency of Thymol and Propolis Extract in Controlling Gut Parasite Vairimorpha (Nosema) ceranae in Honey Bee, Apis mellifera

Honey bees, vital agricultural pollinators, suffer significant losses due to the pathogen Nosema ceranae. Fumagillin, utilized to prevent nosemosis, poses a hazardous risk. This study aims to investigate the potential of natural thymol and propolis extract in combating Nosema infection in honey bee colonies. The evaluation will be conducted through qPCR to quantify the effects at the molecular level, and histopathological analysis to examine tissue damage and cellular responses, providing a comprehensive understanding of the extracts' efficacy in controlling this parasitic infection. In this experiment, infected honey bee colonies were divided into four treatment groups: (1) untreated, (2) propolis treatment (3 g/L), (3) thymol treatment (0.1 g/L), and (4) a combined treatment with both thymol and propolis. Molecular identification of Nosema was carried out using specific primers and reduction in infection was measured using qPCR of the copy number gene for Nosema. Histopathological changes were performed in honey bees midgut. Results showed N. ceranae detection in an untreated colony using PCR, with amplified fragment 220bp, the sequence of the amplified fragment was assigned in GenBank with accession number PP239351 and N. ceranae was closely related to other N. ceranae strains. Gene expression of N. ceranae decreased in honeybee colonies treated with thymol and propolis extracts, and their mix of both extracts showed better results. The light and TEM micrographs of midgut cells demonstrated that treatment with propolis and thymol improved the midgut epithelial cells of honey bees, reduced parasite infection, and led to the disappearance of various spores and the presence of proliferating small epithelial digestive cells containing the empty spores of the parasite. It can be concluded that thymol and propolis extract show potential in combatting Nosema and have positive effects on honey bee health.