First Report of Scent Collection by Male Orchid Bees (Hymenoptera: Apidae: Euglossini) from Terrestrial Mushrooms
2010-07-01

Orchid bees (Apidae: Euglossini) are important pollinators of several angiosperms in the Neotropics, especially orchids (Dodson and Frymire, 1961; Dressler, 1968; Ramirez et al., 2002). Orchid bee males visit flowers that offer fragrances as resources to them as pollinators. This association is known as the ‘‘Perfume Flower Pollination Syndrome’’ (Vogel, 1963; Dressler, 1982). To collect fragrances, the males use their forelegs to adsorb scents that are subsequently stored in special structures located in their hindlegs (Dressler, 1982). Over the course of their lives, male orchid bees visit several plant species to collect floral sources, yielding a mixture of species-specific fragrances that has been shown to be correlated with a male’s age (Eltz et al., 2003; Zimmermann et al., 2006, 2009). These fragrances are used as part of the males’ displays at mating sites to attract females (Kimsey, 1980; Stern, 1991; Eltz et al., 2005a, b; Zimmermann et al., 2006) and it has been proposed that the fragrance mixture displayed by males could indicate mate quality to females (Kimsey, 1980; Eltz et al., 2003; Roubik and Hanson, 2004; Eltz et al., 2005a). However, this hypothesis has been difficult to test due to the short copulation time (,10 sec) and scarcity of observations describing the mating behavior in orchid bees (Stern, 1991; Eltz et al., 2003; Zimmermann et al., 2006, 2009). Although perfume flowers depend on orchid bees for reproduction, several studies have shown that this dependency is not reciprocal (Ackerman, 1983; Whitten et al., 1993; Pemberton and Wheeler, 2006; Cappellari et al., 2009). In addition to perfume flowers, orchid bees are known to collect scents from nonfloral sources like the surface of rotting wood, fruits and seeds, leaf litter, insecticides, and fragrant leaves (Roberts et al., 1982; Ackerman, 1983; Whitten et al., 1989, 1993; Ramirez et al., 2002). Here, we report the first field observations on volatile collection by males of Eufriesea violacea Blanchard on mushrooms growing in the ecotone between the Atlantic rainforest and the higher elevation Araucaria forest (600–1000 m ASL) of southern Brazil. The observations were conducted at the Forest Reserve Pro-Mata (FRPM), Sao Francisco de Paula, Rio Grande do Sul, Brazil (29u309050S, 50u109000W). This 5,000 ha area is characterized by patches of Araucaria trees, deciduous forest, shrub vegetation, and grasslands (Bertoletti and Teixeira, 1997). FRPM is located at the edge of the Araucaria plateau at a higher slope of the Atlantic rainforest remnants, and approximately 50 km from the eastern coast of Rio Grande do Sul. This area is considered the southern distribution limit of orchid bees in the Neotropical region (Wittmann et al., 1988). Bee vouchers were deposited at the LPB collection of the PUCRS Museu de Ciencias e Tecnologia in Porto Alegre, Brazil. Observations were made on the 27th of December, 2001, between 16:00 and 17:00. Six males of E. violacea were observed to collect volatiles from a fruiting body of a basidiomycete mushroom in a patch of forest (Fig. 1A). The males landed on the mushroom and scratched the lamellar gills with their forelegs. Short flights were undertaken after scratching the gills to transfer substances to their hind legs. Males displaced each other for a position close to the gills. The gills were entirely damaged at the time when we collected the mushroom which impaired its proper identification. Volatile collection at another mushroom was subsequently observed on January 5th, 2003, in an area close to the first observation site, when a single male was seen to scrape a fruiting body of a basidiomycete mushroom. The bee’s behavior followed the same pattern as previously observed: first the male scraped the fruiting body with its forelegs, and then hovered over the fruiting body to transfer collected substances to the hind legs. Based on the photographs