Devaluation of sucrose 1 M.

The graph shows the performance (percentage of proboscis extension responses or PER) during (a) an odor-sucrose association in which the response to the odor (conditioned stimulus or CS) was quantified, and during (b,c) a test phase following a devaluation phase in which responses to the sugar (US; see b) and to the odor (CS see c) were quantified in paired and unpaired groups of bees experiencing or not an association between sugar and either distilled water, quinine 10 mM, LiCl 140 mM or amygdaline 1 mM (319 bees in total). (a) All bees learned the odor-fructose association. The graph shows the pooled acquisition performance of all eight groups of bees. (b) Ingestion of quinine, LiCl and amygdaline did not diminish US responsiveness with respect to a water control. Bees responded maximally to sucrose (100% PER). Responses of paired and unpaired groups were similar. (c) Ingestion of quinine, LiCl and amygdaline decreased CS responsiveness with respect of a water control. Responses to a novel odor remained low and equivalent in all groups. Different letters indicate significant between-group differences.