2.1.2.1. Sampling period and sampling frequency

To gain information on how amounts and prevalence of infections change over time, it is necessary to monitor changes over more than one year. Samples should be taken with at least monthly intervals during the period when colonies can be opened without adverse effects on colony survival. For higher resolution of the temporal dynamics of infections, sampling must be bi-weekly or even weekly during periods of rapid change of infection prevalence, as described for N. apis during early spring. Refer to section 2.1.1.1. sampling honey bees.