Geographic and Seasonal Variation in Fragrance Choices and Preferences of Male Euglossine Bees

Abstract

Variation in choices and preferences for fragrances are examined for a large portion of the euglossine bee assemblages of Barro Colorado Island (BCI) and Cerro Campana, Panama. Census data were obtained from a year-long baiting program utilizing 16 chemical attractants. Interand intraspecific variation in fragrance choices occurred. Within sites, fragrance choices of species overlapped considerably, but each species was attracted to a unique set of baits. For some species, choices of infrequently visited chemicals differed among sites. The five baits preferred by most species were the same for both sites. Geographic variation in intraspecific fragrance preferences occurred for seven of eleven species that were abundant at both BCI and Cerro Campana. Seasonal variation in fragrance preferences occurred for 16 of 21 species on BCI. The lack of seasonal shifts was not related to the number of fragrances to which a species was attracted. Indirect evidence exists for age-dependent shifts in chemical preferences by bees. Substantial intraspecific variation in fragrance preferences occurs and is related to some combination of season, age, and geography. The degree to which natural fragrances are available and genetic differences among individuals affect variation in choices and preferences for fragrances remains unknown. THE NATURAL HISTORY OF THE NEOTROPICAL Euglossini (Apidae), commonly known as orchid bees, is unusual and male behavior is both perplexing and intriguing. Male bees utilize the same nectar sources as females (Ackerman 1985), and their foraging behavior at these flowers is similar (Ackerman et al. 1982). Males differ from females in that they have no role in nest construction or in cell provisioning. Furthermore, male bees collect fragrances from a variety of sources, including rotting fruits and wood, tree bark, exposed roots, and flowers (Ackerman