CHEMICAL AND ETHOLOGICAL STUDIES OF POLLINATION IN THE GENUS OPHRYS (ORCHIDACEAE)

Results of chemical analyses of volatile compounds from flowers of 30 Ophrys taxa, from odour attracted insects, and the pollination biology of Ophrys orchids are reviewed. Chemical similarities were found between the volatiles released from Ophrys flowers and the insect glands in a number of pollination systems: (i) Ophrys taxa in the section Fusci-Luteae and bees of the genus Andrena s.l.; (ii) Ophrys taxa in the form complex Arachnitiformes-Araneiferae and bees of the genera Andrena s.l. and Colletes; (iii) Ophrys insectifera and its two digger wasps pollinators Argogorytes mystaceus and A. fargei and (iv) Ophrys scolopax heldreichii and the males of the bee Tetralonia cressa. Ethological field tests indicated chemical mimesis in certain pollinator systems. Aliphatic 1-alcohols and 2-alcohols and the terpenes geraniol, geranial, linalool, and E,E-farnesol are regarded as key attractive compounds, present especially in the Ophrys section Fusci-Luteae, the form complex Arachnitiformes-Araneiferae, and in a number of bee species in the genus Andrena s.l. © 1990.