Figure 1.
The observation chamber was connected to the main flight arena through a sliding transparent Plexiglas sheet (only source of illumination). The chamber faced a vertical cardboard on which six coloured discs (blue and yellow) were displayed. The test bumblebees were first individually tested for their naive preference by recording the number of choices for each coloured disc for five minutes. Each test bee was subsequently held in the observation chamber on its outbound journey towards the flight arena, while artificial bees were presented in front of the yellow disks during the 10 minute observation phase. Demonstrator bees were then removed from the arena and the spatial arrangement of the coloured disks on the presentation board was modified. The test bee was finally released into the arena and the number of cumulative choice for each colour was recorded for five minutes. The diagram is not true to scale.
Figure 2.
Percentage of choices (mean ± SEM) for the blue colour vs. yellow colour in the non-rewarding tests. The dashed line indicates random choice level. White and black bars show results from individuals of respectively the first and second colony used in this experiment. There was no significantly influence of the colony origin of the tested individuals. Within each treatment, the bars on the left correspond to the naive preference of the test bees without prior exposure to these colours. The bars on the right present colour preference of the same bees after the observation period in which they observed artificial bees displayed in front of the yellow stimuli. The observation period only had a significant influence on bees’ colour preference if the artificial bees were moving and presented as short distance (15 cm) from the observation chamber during the observation phase.