Abstract
Male orchid bees (Euglossini) pollinate 10% of the neotropical orchid flora while collecting floral scents, which they store and accumulate in hind tibial pouches. The purpose of these fragrances is unclear, as is the context, timing and mechanism of their possible exposure. Here we show for the first time that males expose and relocate their fragrances during courtship display. We present high-speed video analyses revealing an intricate and repetitive leg movement performed by displaying male Euglossa cognata. The behavior involves several morphological structures of hitherto unknown function and suggests transfer of substances from the hind tibia to a contralateral mid-tibial tuft of hairs. Body-side-specific fluorescent dye application and consecutive detection of signals on males after display confirmed this transfer. Deposited on the mid-tibial tufts, the fragrances are ideally placed in order to become ventilated by jugal combs on the wing bases, as previously suggested by Bembé (in Apidologie 35:288–291, 2004). Being clearly distinct from motor patterns involved in fragrance collection, the described movement is continuously performed by displaying males, suggesting an equally continuous exposure of volatiles. Although the findings strengthen, the view that the volatiles serve as attractants in the context of mating behavior, the signal addressee, conspecific males or females, has yet to be found.
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Acknowledgements
We thank the Smithsonian Tropical Research Institute, D. Roubik, H. Greven, M. Brenner, C. Krüger and G. Schuster for providing technical assistance and logistical support. Benjamin Bembè, H. Greven, C. Brühl and the members of the Sensory Ecology Group seminar helped to improve the manuscript. This study was supported by the Deutsche Forschungsgemeinschaft (EL 249/2-1). The experiments complied with the “Principles of animal care”, publication No. 86-23, revised 1985 of the National Institute of Health, and also with the current laws of the countries in which the experiments were performed.
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Eltz, T., Sager, A. & Lunau, K. Juggling with volatiles: exposure of perfumes by displaying male orchid bees. J Comp Physiol A 191, 575–581 (2005). https://doi.org/10.1007/s00359-005-0603-2
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DOI: https://doi.org/10.1007/s00359-005-0603-2