The tooting and quacking vibration signals of honeybee queens: a quantitative analysis

Summary

The behaviour of young honeybee queens and of worker bees was studied in an observation hive. Tooting and quacking signals emitted by the queens were recorded as airborne sound and as substrate vibrations of the combs by means of a microphone and a laser vibrometer, respectively. The fundamental frequency component is larger than the harmonics when the signals are measured as vibration velocity, and it is argued that the signals are carried mainly by the fundamental frequency component. The frequencies emitted depend on the queens' age, and the tooting syllables contain a frequency sweep. These observations may explain some of the very diverse frequency values reported in the literature. The fundamental carrier frequencies of the toots and quacks overlap, but the tooting syllables have longer rise times than the quacking syllables. Recordings of the vibration of cells in which queens were confined allowed us to measure the threshold for the release of quacking in the confined queens by artificial toots and by natural toots from emerged queens. Artificial toots with long syllable rise time are more efficient in releasing quacking responses than are toots with short syllable rise time. This observation may suggest that the bees recognize these signals mainly by their temporal structure. A comparison of the threshold, emission level, and attenuation with distance, suggests that these and other vibration signals are used by honey bees only for local communication within a restricted area of the comb.