Chapter 6 - Honey bee pollination ecology

Abstract

Pollinators require reliable nutritional intake from plants, in the form of pollen and nectar, while many plants rely on pollinators for reproduction. Bees employ a hierarchical decision-making process when foraging for pollen and nectar as they select which patch, plant species, individual plant, inflorescence, and flower to visit. Honey bees exhibit high flower constancy and high patch fidelity. Various visual traits, including floral display size and flower color, together with olfactory traits play important roles in attracting bees to specific plant species and to individual plants within a species, thereby influencing bee decisions when foraging for pollen and nectar. The relative importance of visual and olfactory traits, and their combined effects can vary when bees visit distinct plant species. Moreover, bees can learn to associate both visual and olfactory traits with rewards. A floral trait strongly associated with a reward could serve as an honest signal to a bee and lead to preferential visits to a plant species or individual plants. We review the evidence for both inter- and intraspecific honest signaling by plants. Variation in floral traits leading to preferential bee visitation and differential plant reproductive success provide the necessary conditions for pollinator-mediated selection and coevolution between plants and their pollinators. While visual and olfactory floral traits attract honey bees to plants, foraging bees can assess floral rewards through variable sensitivity thresholds that facilitate the decision of a bee to continue or abandon reward collection from individual plants or a plant species. Honey bees can perceive sucrose concentration and quantity, and may detect pollen sourced amino acids and fatty acids. We discuss what is known about honey bee foraging behavior and resource perception, including the less explored aspects of water and resin collection, and the use of plant secondary metabolites by honey bees. We end with a review of predation detection and its impact on bee foraging.