Liebefeld Estimation Method
Lexikon
The Liebefeld estimation method is a standardized procedure for assessing the strength of a bee colony far more precisely than by simply counting occupied comb spaces between the frames.
The Liebefeld estimation method is a standardized procedure for assessing the strength of a bee colony far more precisely than by simply counting occupied comb spaces between the frames. It goes back to work by the researcher Jeffree in the 1950s and was further developed in the early 1970s by Hans Wille and Luzio Gerig at the Swiss Centre for Bee Research in Liebefeld near Bern, today's bee research group of Agroscope. There it is still used today for the scientific observation of colony development over the course of the season.
In use, each side of each comb is assessed individually. For the bees, one estimates what proportion of the area the bees actually present would occupy if mentally pushed together, graded in quarters up to a full comb side. For brood and stores, a frame divided into square decimeters by strings is used, or alternatively a tape measure, to record open brood, capped brood and food stores by area. From these areas, the number of bees and the number of brood cells are then calculated using fixed conversion factors.
The conversion is based on the fact that a fully occupied comb side carries a different number of bees depending on the frame size: around 1,200 for the Swiss size, around 1,400 for Dadant, around 1,000 for Zander, around 1,100 for Langstroth, and around 900 bees for German Normal. On one square decimeter of densely occupied comb area, an average of around 130 bees and around 400 brood cells is assumed.
In practice, the Liebefeld method is mainly used where precise, long-term comparable progress monitoring matters more than a quick assessment, for example in bee research or when observing colony development over the course of a year. A check on two colonies over a full season showed very good agreement between the estimated values and actual weighing and planimetry measurements, while open brood is somewhat harder to estimate exactly than the clearly visible capped brood, because its area is less easy to see.
Quellen (3)
- Überprüfung der Schaetzmethode zur Ermittlung der Brutflaeche und der Anzahl Arbeiterinnen in freifliegenden Bienenvoelkern, Imdorf et al. 1987, Agroscope / Schweizerisches Zentrum für Bienenforschung
- Lehrgang zur Erfassung der Volksstärke, Imdorf & Gerig, Agroscope / Schweizerisches Zentrum fuer Bienenforschung
- Die Liebefelder Schätzmethode: Das Gefühl mit Verstand untermaürn, Schweizerische Bienen-Zeitung