Figure 1.
Experimental design to test the effect of the Earth's magnetic field on the recruitment success of waggle-dancing honeybees.
(A) bottom: waggle dancing honeybee describing a figure 8 on the vertical comb in a hive; top: the angle of the waggle run relative to vertical correlates with the angle between the target food source and the azimuth of the sun (angular direction); (B) observation hive (see arrow) inside a triaxial Helmholtz coil system capable of cancelling or arbitrarily modifying the local geomagnetic field; (C1) components (blue vectors) of the local (unmodified) geomagnetic field (Bearth); (C2 & C3) manipulation of field components (red vectors) to cancel the local geomagnetic field (C2) or to rotate its declination to the East (C3).
Figure 2.
Effect of suppressing the ambient magnetic field on the recruitment success of waggle-dancing bees.
Boxplots show the mean, median lower and upper quartiles, and ± whiskers (minimum/maximum data points) of the number of honeybee nest mates recruited in morning and afternoon sessions to a feeding station in the presence (control session) or absence (treatment session) of the ambient magnetic field (see Fig. 1B, C2). The presence or absence of the ambient magnetic field had no effect on the number of recruits irrespective of the alignment of the observation hive (East–West: linear mixed effect model analysis; F1,10 = 0.9548, p = 0.35; North–South: linear mixed effect model analysis; F1,7 = 0.9660, p = 0.3).
Figure 3.
Effect of shifting the declination of the ambient magnetic field to the East on the recruitment success of waggle-dancing bees.
Boxplots show the mean, median, lower and upper quartiles, and ± whiskers (minimum/maximum data points) of the number of honeybee nest mates recruited to a feeding station when the hive was exposed to either the ambient magnetic field (control session) or to the magnetic field with its declination shifted East (treatment session) (see Fig. 1, C3). In each replicate (N = 15), treatment and control sessions were run concurrently using a single-frame observation hive with green- or orange-coded bees in each of two separate but identical Helmholtz coil systems (one of which is shown in Fig. 1B). The number of nest mates recruited from hives in treatment or control sessions did not differ (linear mixed effect model analysis; F1,14 = 0.0274, p = 0.87).