Bumblebees' Bombus impatiens (Cresson) Learning: An Ecological Context
The capacities of the bumblebee, Bombus impatiens, for learning and cognition were investigated by conditioning with increasingly complex series of single or multiple tasks to obtain the reinforcer (50% sucrose solution). Through operant conditioning, bumblebees could displace variously sized combinations of caps, rotate discs through various arcs (to 180°), and associate rotation direction with colour (white vs. yellow). They overcame various tasks through experience, presumably by shaping and scaffold learning. They showed incremental learning, if they had progressed through a series of easier tasks, single caps with increasing displacement complexity (to left, right, or up) or of balls with increasing masses, but could not complete the most difficult task de novo. They learned to discriminate the number of objects in artificial flower patches with one to three nectary flowers presented simultaneously in three compartments, and include chain responses with three other tasks: sliding doors, lifting caps, and rotating discs presented in fixed order. Pattern recognition and counting are parts of the foraging strategies of bumblebees. Multiple turn mazes, with several dead ends and minimal visual cues, were used to test the abilities of bumblebees to navigate by walking and remember routes after several days. They rapidly learned these mazes and remembered the routes even after 16 days. Bumblebees could learn from each other, socially by imitation, observation, and communication within the nest. They were slower to learn to forage with dead conspecific models than with living ones, whether nest-mate or non-nest-mate. Bees that had no opportunity for social learning were unable to forage. The array of experimental approaches I used for training bumblebees and my results have expanded the scope and understanding of the complexity of invertebrate learning and cognition in the context of comparative psychology, and have application to ecological and ethological principles of the evolution of learning and cognition.