EXAMINATION OF THE METHOD FOR ESTIMATING THE BROOD AREA AND NUMBER OF WORKER BEES IN FREE-FLYING BEE COLONIES

Original article:  Imdorf, A., Buehlmann, G., Gerig, L., Kilchenmann, V., Wille, H. (1987)

“Überprüfung der Schätz Methode zur Ermittlung der Brutfläche und der Anzahl Arbeiterinnen in freifliegenden Bienenvölkern”

Apidologie 18 (2), 137-146, DOI: 10.1051/apido:19870204

Translated from German

The ‘Liebefeld method’ for estimating the number of adult worker honey bees (bees) and the areas of open and capped brood cells was re-examined in 1984. The necessary checks were carried out every three weeks from April to October in two free-flying bee colonies.  To begin with, we estimated the number of bees and the area occupied by the brood cells, then compared our estimates with the results obtained by weighing or measuring (planimetry).  There was a high correlation between our estimates and the measurement results for both the number of adult workers (r² = 0.967; n = 18) and for the capped brood cells (r² = 0.987).  For the open brood cells, the correlation was lower (r² = 0.654). The total estimated brood area during the experiment exceeded the measured values by 1.6% in one of the colonies and by 5.4% in the other. Estimates of the number of adult workers were regularly too low.  This discrepancy can be rectified by adopting 1200 adult workers rather than 1100 as the standard population of one face of a comb (Swiss format = 921cm²).  This method enables the dynamics of honey bee colonies to be determined quickly and accurately, with minimal disturbance of the bees.