Ingeborg Beling and the time memory in honeybees: almost one hundred years of research

Abstract

Bees are known for their ability to forage with high efficiency. One of their strategies to avoid unproductive foraging is to be at the food source at the right time of the day. Approximately one hundred years ago, researchers discovered that honeybees have a remarkable time memory, which they use for optimizing foraging. Ingeborg Beling was the first to examine this time memory experimentally. In her doctoral thesis, completed under the mentorship of Karl von Frisch in 1929, she systematically examined the capability of honeybees to remember specific times of the day at which they had been trained to appear at a feeding station. Beling was a pioneer in chronobiology, as she described the basic characteristics of the circadian clock on which the honeybee's time memory is based. Unfortunately, after a few years of extremely productive research, she ended her scientific career, probably due to family reasons or political pressure to reduce the number of women in the workforce. Here, we present a biographical sketch of Ingeborg Beling and review her research on the time memory of honeybees. Furthermore, we discuss the significance of her work, considering what is known about time memory today - nearly 100 years after she conducted her experiments.

Keywords: Circadian clock; Foraging; Honeybees; Ingeborg Beling; Karl von Frisch; Time memory.

Fig. 1

a Ingeborg Beling in 1929. Courtesy: Ingrid Bettin-Heitmann. b Ingeborg Beling’s PhD certificate. The document, written in Latin, lists, besides her name, the names of the rector of the University of Munich, Oswald Bumke, and the Dean of the Faculty of Philosophy, Sect. 2, Alexander Wilkens. It also shows the grade (magna cum laude), the title (in German) of her dissertation, Über das Zeitgedächtnis der Bienen (Time Memory in Honeybees), and the date of the award, February 27, 1929. Courtesy: Universitätsarchiv München (UAM OC-Npr-1928–29)

Fig. 2

Table-figure showing time memory after training field bees at 3 daytimes. Training times are shaded in the figure: 7:30–9:00, 13:00–15:00, 17:45–19:30. Six training days preceded the test day. Out of 19 marked bees, 19 visited the feeder on the observation day, without food presented. Individuals are listed with marked numbers. Bees are counted in time bins of 30 min in daytime hours 5 to 20. (Adapted from Beling .)

Fig. 3

Table-figure demonstrating appearance of the bees at the feeder clearly before the trained time in a constant room experiment with low constant light (see inset). Training time is shaded in the figure: 18:00–20:00. Training took place over 12 days. 45 out of 50 marked bees (individuals with numbers) and additional unmarked bees (gray squares) visited the feeder on the observation day without food present. ‘w’ = white,‘g’ = yellow marking colors. Counts of ‘marked’ or ‘unmarked’ bees are beneath the time scale (time bins of 30 min in a full 24 h cycle starting at 8 am). (Adapted from Beling .)