Pollinator attractions and speciation in wasp-flowers

Wasp-flowers exhibit physiological and morphological adaptations for the attraction of pollinating social wasps. Using a combination of behavioral experiments, electrophysiological investigations, and chemical analyses we are investigating in a comparative approach the pollinator attracting floral volatiles in wasp-flowers of the nectar rewarding orchid genus Epipactis and of the non-rewarding orchid genera Stepheniella and Dendrobium.
Our data show, that prey mimicry is a common syndrome to attract foraging wasps for pollination in many species of wasp-flowers. We found that all wasp-pollinated species of Epipactis emit green leaf volatiles (GLVs), which are attractive to foragers of the social wasps Vespula germanica and V. vulgaris. GLVs are emitted by plants that are attacked by herbivorous insects, which are common prey items for social wasps. Our results showed that Epipactis flowers mimic GLVs in order to attract prey hunting wasps for pollination.
More specific compounds are produced in the non-rewarding wasp-flowers D. sinense and S. satyrioides. Both mimic alarm pheromone compounds that are used by their pollinators in order to find prey items.
Presently we are investigating speciation and species isolation in the Epipactis helleborine group

Coworker: Jennifer Dietel  

Collaborations: Wittko Francke (University of Hamburg), Salvatore Cozzolino (University of Naples), Yannick Städler (University of Vienna)

Funding: Arbeitskreis heimischer Orchideen

Epipactis helleborine and wasp pollinator (Photos J. Brodmann)
Dendrobium sinense and wasp pollinator (Photo H. Paulus)