Fig. 5. The presence of sucrose in the reward strongly affects the ability of honey bees to recall the olfactory CS. Pollen foragers were conditioned with the APC protocol, the antennal-stimulation-alone (AC) protocol or a protocol where the antennae were stimulated with sucrose solution but the subject was fed water (ACW). (A) The rate of acquisition was greatest for the APC protocol (lreg; ²₂=7.80, P=0.040) (N_APC=69; N_AC=58; N_ACW=68). (B) When tested immediately after conditioning, the level of response of subjects to the CS during the first recall trial was not significantly different for the three protocols ( ²₂=1.60, P=0.449) (N_APC=35; N_AC=29; N_ACW=31). After 24 h, the response of the AC and ACW subjects was significantly lower than the responses of the APC subjects ( ²₂=9.21, P=0.010) (N_APC=34; N_AC=29; N_ACW=37). ^*P<0.05.