Geräuschanalyse der Tanzlaute der Honigbiene (Apis mellifica) in unterschiedlichen magnetischen Feldsituationen

Summary

The sounds produced by forager bees during the “straight run” of their waggle-dances show significant periodic variations throughout the day, as regards both single pulses (Einzelton) and the sequence of vibrational pulses (Vibrationsstoßfolge).

The daily courses of these two components are strongly correlated with each other, and also correlated with the daily variation in misdirection (“Mißweisung”) in the bees' dances, and thus with the periodic variations of the intensity of the earth's magnetic field (Figs. 3 to 5).

Thus, the variations in the sounds produced represent at the same time the daily course of misdirection.

Although individual bees produce sounds of different basic pitches (Basistonlagen) — with maximum wavelengths of the two components mentioned — the absolute range of change is about the same for all dancing bees (single pulses: 0.3 ms/10° misdirection, sequences of vibrational pulses: 2.0 ms/10° misdirection).

Amplification of natural field strength by a factor of about 3 to 5 does not abolish the strong correlations existing between the two sound components and misdirection; the range of changing, on the contrary, increases with the amplification of field strength (Figs. 6 and 7).

Under conditions that eliminate misdirection, e. g. compensation for the magnetic field (Figs. 8 and 9) or dancing on a horizontal comb — regardless of whether the observations are done under natural field strength (Fig. 10) or following artificial amplification of field intensity (Fig. 11) — the dancing bees produce their basic pitches throughout the day. On the vertical comb, the same phenomenon is noticed at the socalled zeropoints, under conditions of both normal and increased field strength.

If bees are foraging far away from their hive, the sounds they produced when they return always start from their individual basic pitches and adapt, within a few minutes, to the wavelengths characteristic of the prevailing situation as regards field strength and dancing angle (Fig. 12).

In general, the organization of the sounds essentially confirms former results, although their mean frequency range is somewhat higher (278 Hz for the single pulse and 33 Hz for the sequence of vibrational pulses resp.).

A peculiar feature of the dance of only two bees is described, the so-called “continuous sound”. These two bees produced sounds both during the tail-wagging run and the return half cycle.

The general mechanism of the field effect and the mechanism of reception of magnetic stimuli are discussed, as well as the possibility of sound communication in honeybees.