22.214.171.124.6.1. Colony health status
xColonies should be regularly monitored for the occurrence of diseases (including varroa infestation level, see Dietemann et al., 2013) and any clinical sign should be noted. Prior to the exposure to pesticides, no clinical signs should be observed. Colonies should not be taken if they have received a treatment against varroa in the last 4 weeks prior to the trial. If the varroa treatment is administered during the trial period, the treatment protocol (date of the treatment, product, duration, quantity applied and efficacy observations) should be noted.
Delaplane et al., 2013b describes recommendations concerning colony size, which should be as homogeneous as possible. As field tests should resemble as much as possible realistic conditions, colonies’ population would differ depending on the time of the year in which the trial would occur. Colonies of 15,000 individuals would be characteristic of a beginning of the season or overwintering period, while colonies of approx. 50,000-60,000 individuals would be characteristic of the middle of the season (EFSA, 2012). These estimations however, might vary geographically. The evolution of the colony health status along the trial is one of the observations described later in this method.