How Bumblebees (Bombus impatiens) Use Visual Cues of Conspecifics under Stressed and Rewarded Internal States
by Jaime Christiaanse
Supervisor: Dr. Levente Orban
Abstract:
Bumblebees are social animals that use
visual information about other bees to choose flowers. Workers prefer flowers
that are occupied by another bee when the occupier is large relative to the flower,
and when occupied flowers are relatively rare in the field compared to empty flowers.
Here, we investigate reasons under which the preference for occupied flowers
varies with the internal state of B. impatiens workers. To manipulate the
workers' internal state, we present workers with a droplet of 1M rewarding
sugar solution, 1mM aversive quinine solution, or shake workers for 3s or 10s
prior to releasing them into a 12-arm radial arm maze. In Experiment 1, we
found significant choice proportion deviations towards occupied patterns in all
three conditions: 10s squish (GP = 8:586; p = :004), 3s squish (GP = 18:057; p
<:001) and control (no exposure) (GP = 52:159; p < :001). In Experiment
2, there was a significant preference for occupied flowers in sugar exposed
workers (GP = 8:025; p = :005), but no preference for occupied flowers in
quinine exposed workers (GP = 2:297; p = 0:13). These results suggest that
quinine removed the preference for occupied patterns seen in the sugar exposed
and squished workers. Previous research has viewed quinine, shaking, and
squishing as equivalent manipulations for invoking negative internal states in
insects. Our findings indicate that they are not equivalent, since quinine
evoked an internal state which drove workers away from their preference for
occupied flowers, and squishing did not.