Orchid-pollinator network in Euro-Mediterranean region: What we know, what we think we know, and what remains to be done

Abstract

Facing the threat of global change, there is an urgent need to document our current knowledge about the interactions between plants and their pollinators, especially for species with specialized pollination strategies. We review orchid-pollinator networks in the Euro-Mediterranean region by providing an overview and a critical analysis of our current knowledge on pollination interaction. This review is organized in three parts: what we know, what we think we know and what remains to be done. Firstly, by relying on the recent orchid-pollinator network analyses, we investigate in detail what we know in terms of pollinator preferences as well as in terms of orchid pollination strategies. Even if at least one pollinator species is recorded for about half of the species of orchids in the Euro-Mediterranean region, we show that our knowledge of the orchid pollinator interaction stays largely imperfect. Secondly, we have identified several biases in what we think we know about orchid-pollinator interactions, by i) examining potential mistakes about species identification, but also potential biases induced by preconceived beliefs about the highly specialized pollination of Ophrys and also about the expected abundance of pollinators on nectar-producing orchids and ii) revealing a novel and promising research avenue concerning the sex of the pollinator and the strategy used by orchids to attract their pollinators. Thirdly, we have identified what remains to be done to give priority to the Euro-Mediterranean countries and orchid taxa which are still neglected or insufficiently studied. Finally, we propose several dos and don'ts to improve our knowledge of orchid-pollinator network by using a structured approach that is common to all field naturalists and scientists working on this fascinating topic.