Exocrine secretions of bees : VI. Unsaturated ketones and aliphatic esters in the Dufour's gland secretion ofDufourea novaeangliae (Hymenoptera: Halictidae)

Olfactory eavesdropping between two competing stingless bee species

Foragers can improve search efficiency, and ultimately fitness, by using social information: cues and signals produced by other animals that indicate food location or quality. Social information use has been well studied in predator-prey systems, but its functioning within a trophic level remains poorly understood. Eavesdropping, use of signals by unintended recipients, is of particular interest because eavesdroppers may exert selective pressure on signaling systems. We provide the most complete study to date of eavesdropping between two competing social insect species by determining the glandular source and composition of a recruitment pheromone, and by examining reciprocal heterospecific responses to this signal. We tested eavesdropping between Trigona hyalinata and Trigona spinipes, two stingless bee species that compete for floral resources, exhibit a clear dominance hierarchy and recruit nestmates to high-quality food sources via pheromone trails. Gas chromatography-mass spectrometry of T. hyalinata recruitment pheromone revealed six carboxylic esters, the most common of which is octyl octanoate, the major component of T. spinipes recruitment pheromone. We demonstrate heterospecific detection of recruitment pheromones, which can influence heterospecific and conspecific scout orientation. Unexpectedly, the dominant T. hyalinata avoided T. spinipes pheromone in preference tests, while the subordinate T. spinipes showed neither attraction to nor avoidance of T. hyalinata pheromone. We suggest that stingless bees may seek to avoid conflict through their eavesdropping behavior, incorporating expected costs associated with a choice into the decision-making process. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00265-010-1080-3) contains supplementary material, which is available to authorized users.

The chemical ecology and evolution of bee–flower interactions: a review and perspectivesThe present review is one in the special series of reviews on animal–plant interactions

Bees and angiosperms have shared a long and intertwined evolutionary history and their interactions have resulted in remarkable adaptations. Yet, at a time when the “pollination crisis” is of major concern as natural populations of both wild and honey bees ( Apis mellifera L., 1758) face alarming decline rates at a worldwide scale, there are important gaps in our understanding of the ecology and evolution of bee–flower interactions. In this review, we summarize and discuss the current knowledge about the role of floral chemistry versus other communication channels in bee-pollinated flowering plants, both at the macro- and micro-evolutionary levels, and across the specialization–generalization gradient. The available data illustrate that floral scents and floral chemistry have been largely overlooked in bee–flower interactions, and that pollination studies integrating these components along with pollinator behaviour in a phylogenetic context will help gain considerable insights into the sensory ecology and the evolution of bees and their associated flowering plants.