Bumblebees prefer shorter over longer strings and connected over disconnected ones in string-pulling tasks but prioritize connectivity over spatial proximity when the two are in conflict.

Abstract

We aimed to investigate the trade-off strategies between efficiency and accessibility employed by bumblebees (Bombus terrestris) when solving string-pulling tasks. In these tasks, bees were required to choose between two strings, which varied in length, and whether or not they were connected to an artificial flower. Our results indicate that when presented with strings of varying lengths connected to artificial flowers containing rewards, the bees consistently preferred the shorter string. Instead of learning the string length experienced during training, the bees showed a preference for the shorter string, even after being trained with a longer one. Bumblebees were also capable of selecting connected over disconnected strings, even when proximity served as a confounding factor. These findings demonstrate that bumblebees flexibly deploy a diversity of strategies to solve string-pulling tasks, shedding light on their problem-solving capabilities when tackling non-natural spatial and object manipulation tasks.