Honeybee age and inoculum concentration as factors affecting the development of Nosema ceranae infection

Abstract Nosemosis is one of the most widespread honeybee diseases. Its epidemical state can be determined as panzootic. The infectious agents are the microsporidia Nosema apis and N. ceranae. Numerous substances and preparations were tested in order to find a way to combat this disease. However, methodology used in artificial infection experiments is not unique; concentrations of N. ceranae spores in inoculum vary as well as the age of honey bees when they are infected. In addition, the disease itself is still relatively poorly understood. This makes the interpretation of such research difficult. The aim of this study is to investigate the effect of bee age and inoculum concentration on the development of N. ceranae infection. Honeybee workers were collectively infected at the age of 2 and 10 days post-emergence with concentrations of 104, 5 × 104, and 105 spores/bee. While the results indicate a significant effect of both tested factors on the development of N. ceranae, the relationship is not simple, and age alters the pattern of nosemosis development in response to the given concentrations. Highlights The course and the effect of Nosema ceranae infection differed depending on bee age at the moment of infection. The development of the infection differed depending on concentration of N. ceranae spores in inoculum. Concentration of N. ceranae spores had an effect on mortality and syrup intake in 10-day-old bees. Graphical abstract