Spatial encoding of artificial flowers by bumblebees (Bombus impatiens): The contents of memory

A novel methodology allowed simultaneous investigation of three elements of bumblebee foraging behaviour: spatial encoding of flower position, landmark use, and scent marking. Bumblebees were presented with a row of artificial flowers in a flight cage, one flower offering reward (S+). Testing involved empty (i.e., unrewarding) flowers. In Experiment 1, flower covers presumed to be scent marked (old covers) were switched with one of the unmarked covers, or replaced with new, scent-mark-free covers. Results confirmed previous research: presence of old covers influenced response type rather than floral choice. Choice appeared to have been made using memory. In Experiment 2, the S- were moved during testing to change the relative position of the S+. New covers were used for half of the bees. The flower in the same absolute position (wrong relative position) as the S+ was consistently chosen, suggesting that the S- did not function as landmarks. Contrary to Experiment 1, old covers influenced flower choice. Experiment 3 replicated Experiments 1 and 2. Again, bees preferred absolute position, but results suggest relative position was encoded and influenced choice under certain circumstances. The effect of old vs. new covers continued to be inconsistent: choice means were higher with new covers, and probing often occurred on new covers. Finally, when flower array independent (FAI) information and memory for a flight vector were placed in conflict in Experiment 4, bees showed a bias for using FAI cues. Taken together, these experiments show that the definition of a landmark remains to be clarified, the role of scent marking remains elusive, and bumblebees showed a consistent bias for using FAI information to locate a goal. Contributions of this thesis are placed within the context of research with vertebrate species and natural bumblebee foraging behaviour