Bumblebees develop more efficient traplines than honey bees

Central place foraging pollinators, such as bees, tend to learn multi-destination routes (traplines) to efficiently visit known feeding locations and return to their nest. To what extent these routing behaviours are shared across species is unknown. Here we ran laboratory experiments to compare trapline formation and efficiency by foragers of two social bee species that differ in their collective foraging strategies: the solo foraging bumblebee Bombus terrestris and the mass foraging honey bee Apis mellifera. In a simple routing task with four artificial flowers, both bumblebees and honey bees developed a stable route, although honey bees were slower and less efficient to do so. In a more complex routing task with six flowers, only bumblebees developed a stable route. Honey bees took a longer time to discover all flowers and never integrated them in a single route. Simulations of a model of trapline formation show that these inter-specific differences can be replicated by adjusting the strength of a single learning parameter. Comparing bumblebees and honey bees in the same experimental conditions thus revealed key differences in their spatial foraging strategies, potentially driven by social constraints.