18.104.22.168.9.2. Brood and reserves content
The surface of brood and reserves should be monitored before, during and after the trial (see Delaplane et al., 2013b). Estimation of colony strength parameters should be performed close before the crop bloom and one week after. Given that the reserve frames should have been removed before the study, there should be visual controls of the food content of the colony. The observation should be repeated once weekly up to the 42 days of the duration of the trial. In case a more intensive data gathering method is used (e.g. the Liebefelder method presented first in Imdorf, 1987 and described in Delaplane et al., 2013b), one could reduce the data collection to every three weeks.