Reference: Biol. Bull. 164: 355-395. (June, 1983) ORCHID FLORAL FRAGRANCES AND MALE EUGLOSSINE BEES: METHODS AND ADVANCES IN THE LAST SESQUIDECADE NORRIS H. WILLIAMS' AND W. MARK WHITTEN 2 1 Department of Natural Sciences, Florida State Museum, University of Florida, Gainesville, FL 32611, and 2 Department of Botany, University of Florida, Gainesville, FL 32611 ABSTRACT All species of the Neotropical subtribes Stanhopeinae and Catasetinae (Orchi-daceae) are pollinated exclusively by male euglossine bees which are attracted to and collect the floral fragrances. The orchid-euglossine bee relationship is often highly specific: the flower of a given species of plant may attract males of only one or a few species out of dozens of euglossine species in the habitat. This pollinator specificity is based upon species-specific combinations of floral fragrance compounds which attract only one or a few species of euglossine bees. Such pollinator specificity is an important reproductive isolating mechanism between sympatric interfertile species of orchids. The male bees are thought to use the collected floral fragrance compounds in their own reproductive biology, probably as precursors of their own sex pheromones. INTRODUCTION One of the most striking examples of plant-insect interactions is that involving the male euglossine bees of the American tropics and the orchids they pollinate (Dodson, 1965). Although it was once thought that the male bees became "intox-icated" by the fragrances of the orchids, we now know that the situation is much different. In this paper we will review the progress that has been made since the 1969 paper on biologically active compounds in orchid floral fragrances (Dodson et al, 1969). Some aspects of the biology of this group of insects were reviewed by Dressier (1982), and some aspects of the pollination biology of the orchids were reviewed by Williams (1982). Here we will emphasize the advances made in the collection and analysis of the floral fragrances, and the possible utilization of the floral fragrance compounds in the life of the insect. Euglossine bees are exclusively Neotropical, and for the most part are solitary, communal, or quasisocial (depending on the particular species). There are three free-living genera: Euglossa (approximately 100 species, bright metallic blue, green, or bronze), Eulaema ( \ 3 species, brown or black, or striped hairy bees), and Eufriesea (52 species, metallic or brown/black and hairy). Two genera are nest parasites on the free-living groups: Aglae (monotypic, metallic blue) and Exaerete (5 species, metallic green). Taxonomic, biogeographic, and bibliographic references are given by Dressier (1979, 1982), Kimsey (1979, 1982), and Williams (1978, 1982). The female bees gather food (pollen and nectar) from a variety of plants and they gather resins, mud, and other materials for nest building. The male bees visit some of the same plants as the females for food, but are not tied to the nest. The male bees leave the nest upon hatching and do not return to the nest again. They Received 19 February 1983; accepted 10 March 1983. 355
BioStor
