Laboratory studies examining aspects of scent marking, traplining and remote detection of reward in the foraging bumblebee.

Abstract

Energy from food is essential for the survival of all animals. For decades, bumblebees have been used as model organisms for studying animal foraging strategies. Here, I use bumblebees to examine two foraging strategies: scent marking and traplining. I find that experience and long term memory play an important role in both of these strategies. I show that bees interpret scent marks differently depending on context. They learn to rely on these scent marks to different degrees depending on flower handling time. Bees also learn to associate the same scent marks with high and low rewarding food, which means the same scent promotes and suppresses acceptance of flowers. Contrary to previous speculation, I find that these scent marks are not pheromonal signals specifically evolved to play a role in foraging. Rather they are incidental cues that bees learn to use to improve foraging performance and locate their nesting sites. Experience is also important in developing repeatable stable routes between food sites i. e. traplines. I show that bees required long term spatial memory to gradually form traplines. They reduced their travel distance by linking near neighbour flowers, which did not result in using the shortest routes. Traplining bees were also less likely to revisit emptied flowers and spent less time searching for these flowers. For decades, scientists have used water to control for remote effects of sucrose solution in experiments. I find that bees are able to detect the difference between these two liquids without contact chemoreception. The exact cue they use remains to be determined, but it is not humidity.