Sampling details for detecting and quantifying Nosema spp infection levels in honey bee colonies

For detection of Nosema presence OIE manual prescribes analysis of 60 bees collected from hive entrance. For quantification of infection levels however the same manual prescribes analysis of 10 “older” worker bees.Due to the growing concern that Nosema ceranae may be strongly involved in the colony loss phenomenon, routine analysis of presence of this pathogen in honey bee colonies is becoming more widespread, even in countries where Nosema disease was traditionally not a problem. It is therefore important to establish standard sampling and analysis protocols which couple repeatability and ease of field sampling, and which, together with observations on colony development and health status may provide the basis for the determination of Nosema disease threshold levels. These levels could represent a useful prophylactic tool for beekeepers and limit dissemination of the disease. Here we present comparisons between different kinds of sampling modes and sample sizes, and an overview of Nosema disease in several apiaries in Italy, with observations of seasonal differences.