Signs of the Time: Clocks, Bees and their Forgotten Scientist

Can bees tell the time? In their own unique way – yes. And, understanding how and why could play an important role in increasing hive productivity and improving conservation efforts.

By Dave Black

Ingebord Beling, circa 1929, ‘the bee scientists we all forget about’.

Ingebord Beling, who died in January 1988, is the bee scientist we all forget about. Born in Germany in 1904, and with an academic career that lasted a mere seven years, that isn’t surprising. Beling completed her PhD studies at the University of Munich advised by Karl von Frisch, who became a family friend. It’s not clear why her career was so short. In the pre-war 1930s, marriage and children, and the prevailing Nazi misogyny, are likely to have contributed.

After the award of her PhD she moved to a job with a Berlin-based Institute for Agriculture and Forestry, away from bees, to biocontrol measures for pests and the connection to her future husband. In seven years she had published three papers related to chronobiology (which studies the rhythms and timing of biological events), the last one in 1935, and seven related to pest control. All of course written in German, the other reason she’s been forgotten.

Beling retained a life-long friendship with von Frisch (who died in 1982) and in a fascinating bit of archive film from 1952[i] she can be seen as his, uncredited, ‘assistant’ working in the gardens of his house at Brunnwinkl, near Salzberg, Austria.

Chronos and the Clockwork Cosmos

Beling’s thesis Über das Zeitgedächtnis der Bienen (On the Time Memory of Bees) was published almost 100 years ago in 1929, making her one of the earliest pioneers of chronobiology.[ii] At that time, circadian rhythms and living clocks were unknown.

We will never know what exactly inspired her interest in bees and time. That plants demonstrated daily cycles was known, but usually assumed to be due to alternating day and night. Carl Linnaeus proposed a ‘floral clock’, a Horologium Florae, in 1748 and published the design in his 1751 book Philosophia Botanica. He realised that an intimate knowledge of when certain plants flowered during the day was reliable enough to tell you the time. Unfortunately for the many people subsequently trying to actually plant such clocks, location matters! It turns out to be really complex, your ‘4 o’clock flower’ will be a ‘5 o’clock flower’ to someone somewhere else.

Bees were not known to have any sense of time, but for a long time people had also observed that honeybees would visit certain flowers (or marmalade!) at specific times of the day. Beling would have been aware of other scientists of the time discussing the idea, particularly Hugo-Berthold von Buttel-Reepen (1860-1933), a zoologist and leading figure in German Beekeeping[iii], as well as Auguste-Henri Forel (1848 -1931), a Swiss intellectual with complicated interests and a controversial legacy (eugenics anyone?)[iv]. Beling simply wanted to understand how well bees could remember ‘feeding time’, what the biological relevance of being able to do that was, and what factors might influence the memory of time for bees?

Replacing conjecture

Her controlled experiments showed bees were clearly able to remember feeding times they were trained to, and they could be retrained to new times. They easily recalled times of the day when food is available and turned up to a feeder ‘on time’. In indoor experiments with artificial light and constant environmental conditions she found bees can remember the time of feeding at any day-time or night-time. It didn’t matter if brood was present or not.

Together with Oskar Wahl (another von Frisch disciple) in follow-up experiments they learned that even with food constantly available, the trained bees only visited at the right time, while untrained bees turned up at all times, or not at all. It took a couple of hours to train them, and they remembered for at least six days. It could be shown hunger wasn’t a cue, that bees were not using the sun as their ‘clock’, and that 24hr cycles were all they could manage.

By transporting trained bees around the globe and across continents 25 years later, Max Renner and others were able to prove the ‘clock’ had to be an internal part of bees that, left to its own devices cycled over 20-26 hrs, but which could be synchronised to new day-night periods. To use the jargon, the ‘clock’ was endogenous, circadian, and could be entrained. More recent work has gone on to illustrate how fundamental a ‘clock’ is to a bee’s own biology, regulating and focusing internal molecular processes to make efficient use of its limited resources.

Having a sense of time is clearly useful for bees. Just in terms of foraging, several features of flower plants operate to a temporal rhythm; flower opening, scent release, petal movement, nectar production, and pollen availability, so the ability of bees to learn and co-ordinate their behaviour accordingly is certainly ecologically relevant. Using the sun for navigating and communicating food sources requires a sense of time to compensate for the sun’s apparent motion. What we don’t yet fully understand about a bee’s sense of time is, how the measuring instrument works[v].

Carl Linnaeus (1707-1778), developed the idea of his floral clock in 1748. It works on the principle that flowers open and close at set times of day.

An Ancient Ouroboros

Even the simplest plant and animal cells have clocks, almost everything about life is cyclical. At its most fundamental, a clock is just an oscillator. In everyday life, a pendulum, a balance wheel, or even a quartz crystal all oscillate, the regular ‘tick’ counting the continuum of time. In biology, chemical reactions can oscillate back and forth, repeatedly moving away from an equilibrium point before returning to it[vi]. After a period of time the products of the reaction serve to limit the reaction itself. As far as we know there are two basic types of ‘clock-forming’ reactions, Transcription-Translation Feedback Loops (TTFL) and Post-Transcription Oscillators (PTOs), the former applying to honeybees.

Four genes have been discovered in the honeybee cell nucleus which are used to make the proteins involved in the honeybee clock. Two make (transcribe) proteins that, together, form a complex that activates the last two. These last two genes (DNA) transcribe messenger RNA molecules which make proteins outside the nucleus in a process called translation. The finished proteins are relocated back to the nucleus where they block the activity of the previously formed protein complex[vii].

These genes and proteins are responsible for one endless looping cycle, promoting the manufacture of a product that in time inhibits its own manufacture, a ‘tick’ that has a constant duration. How this cycle becomes synchronised with the outside world is less clear in bees than it is in some other animals. In Drosophila, for example, daylight degrades one of the protein products, changing the dynamic of the cycle in a regular way.

By attaching protein antibodies that stain or fluoresce to one of these ‘clock’ proteins, and to one of the chemical messengers known to be used by animal nerve cells, rough ‘maps’ of the bee brain’s clock have been constructed.

The Social Clock

Socially regulated plasticity in the circadian activity of honey bees. Nurse bees care for the brood without daily rhythms, whereas foragers are typically more active during the day and sleep at night. Division of labour is plastic and socially regulated.

Honeybees, as we know, are all special. Only some of them work outside. In the last few years honeybee chronobiologists have noticed that social bees’ clocks are different to solitary bees’ clocks, and that our social bees emerge without a fully developed clock and no circadian rhythm[viii]. The honey bee is the first animal for which social synchronisation was shown to override synchronisation by light.

Social cues from other members of the colony appear to help nurse bees to mature and develop a circadian rhythm and the ‘clock’ remains strongly influenced by social cues, because foraging bees can revert to nursing without rhythms and young bees can start foraging prematurely with daily activity rhythms[ix]. Young bees isolated from the colony take longer to develop circadian rhythms than bees that have had social contact. Gradual maturation or synchronisation of a clock looks like it might be a feature of social animals, including social mammals like us.

A New Zeitgeist

In the wider world it is the plants, and the climate they inhabit, that are training honeybees, although in some circumstances the bees could be training the flowers. A successful visit by an insect pollinator can advance the time of flower closure and reshape the subsequent timing of flower availability, but no-one has taken a thorough look yet at how bee-clocks and plant-clocks might interact, something potentially quite significant for pollination ecology. How time organises plant rewards or bee activity is almost certainly affecting pollinator competition, and the co-existence and diversity of plant and pollinating species.

Beekeepers might want to pay attention. Those pollinating kiwifruit will have seen the influence anther dehiscence timing has on bee flower visits[x] and there is more to learn. If you follow the complexity of avocado flowering, it’s possible evening opening female flowers are being visited by insects other than bees[xi], and the controversy surrounding bees from mānuka hives on conservation land displacing native pollinators might well be misplaced[xii]. Olfactory conditioning (training) honeybees to crop odours for pollination has some limited success, but as we have seen, timing is everything.

Timing, is everything.

Dave Black is a commercial-beekeeper-turned-hobbyist, now retired. He is a regular science writer providing commentary on “what the books don't tell you”, via his Substack Beyond Bee Books, to which you can subscribe here.

Reference

[i]According to Beling’s daughter Karl von Frisch took her and her mother in his car from Munich to Brunnwinkl, where they were filmed while they worked with bees for an educational film. That film, ‘Die Tänze der Bienen’ (The Dances of Bees). This 21min, soundless B&W gem has been digitised by the Austrian archive Mediathek at https://www.mediathek.at/atom/018AA01B-256-01815-00000484-0189A3E5 Part of this film, appeared in the 2013 documentary ‘More than Honey’ directed by Markus Imhoof. https://www.dailymotion.com/video/x8gq9td.

[ii]Beer, K., Zupanc, G.K.H., Helfrich-Förster, C., 2024. Ingeborg Beling and the time memory in honeybees: almost one hundred years of research. J Comp Physiol A 210, 189–201. https://doi.org/10.1007/s00359-024-01691-9

[iii]Hugo von Buttel-Reepen, (1900) Sind die Bienen Reflexmaschinen? Experimentelle Beitrage zur Biologie der Honigbiene. Biol. Zbl. 20, 177–193

[iv]Auguste-Henri Forel, (1910) Das sinnesleben der insekten: eine sammlung von experimentellen und kritischen studien ueber insektenpsychologie, Orts und Zeitgedächtnis (Memory of Place and Time).  Elfte Studie p.326

[v]Bloch, G., Bar-Shai, N., Cytter, Y., Green, R., 2017. Time is honey: circadian clocks of bees and flowers and how their interactions may influence ecological communities. Phil. Trans. R. Soc. B 372, 20160256. https://doi.org/10.1098/rstb.2016.0256

[vi]Dunlap, J.C., 1999. Molecular Bases for Circadian Clocks. Cell 96, 271–290. https://doi.org/10.1016/S0092-8674(00)80566-8

[vii]Beer, K., Bloch, G., 2020. Circadian plasticity in honey bees. The Biochemist 42, 22–26. https://doi.org/10.1042/BIO04202002

[viii]Beer, K., Helfrich-Förster, C., 2020. Post-embryonic Development of the Circadian Clock Seems to Correlate With Social Life Style in Bees. Front. Cell Dev. Biol. 8, 581323. https://doi.org/10.3389/fcell.2020.581323

[ix]Bloch, G., 2010. The Social Clock of the Honeybee. J Biol Rhythms 25, 307–317. https://doi.org/10.1177/0748730410380149

[x]Broussard, M.A., Howlett, B.G., Evans, L.J., McBrydie, H., Cutting, B.T., Read, S.F.J., Pattemore, D.E., 2022. Pollinator identity and behavior affect pollination in kiwifruit (Actinidia chinensis Planch.). PeerJ 10, e12963. https://doi.org/10.7717/peerj.12963

[xi]Buxton, M.N., Hoare, R.J.B., Broussard, M.A., Van Noort, T., Fale, G.R.T., Nathan, T., Pattemore, D.E., 2023. Moths as potential pollinators in avocado ( Persea americana ) orchards in temperate regions. New Zealand Journal of Crop and Horticultural Science 51, 27–38. https://doi.org/10.1080/01140671.2021.1966480

[xii]See: To Bee or Not to Bee – DOC’s Dilemma, Apiarist’s Advocate, Nov 2022 pp8-13, https://www.apiaristsadvocate.com/_files/ugd/0f980a_73f95967b22442749fe1548cc5f811b2.pdf