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Better than a local lady

Orchids that mimic out-of-town females smell sexy to male bees

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12:40pm, May 27, 2008
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If imitation is the sincerest form of flattery, then some orchid-pollinating bees are being snubbed. Rather than radiating the exact same scent as the local female bees, the orchids mimic the scent of out-of-town females, a new study finds. The male bees, it turns out, seek novelty and are more attracted to the scent of girl bees from a different neighborhood.

The spectacular display of orchid cunning suggests that researchers should look twice at the notion of “flawed mimicry,” especially those where non-exact mimics have been presumed to be imperfect. And research should pay special attention to behavioral and sensory aspects of mimicry systems.

Ophrys orchids are known for exploiting several species of male bees by mimicking the scent of female bees. In the new study, Nicolas Vereecken of the Free University of Brussels in Belgium and Florian Schiestl of the University of Zurich investigated 15 populations of Ophrys exaltata orchids and the pollinators they mimic, Colletes cunicularius bees. Behavioral experiments revealed that the males always preferred the bouquet of non-local female bees to local females and also always preferred the scent of an orchid to the scent of a female bee, local or not, the researchers report in the May 27 Proceedings of the National Academy of Sciences. By manipulating the ratios of the three main notes of the female bees’ sex pheromones to make scents that smelled exactly like the orchids, the researchers confirmed that the plant’s scent ratios were irresistible to the male bees.

Because there are more male than female bees in these populations, and because females are thought to mate only once, the scientists think it is unlikely that the orchids’ antics will drive evolution in female bees.

Watch male bees fall for the orchids' antics:


Flower power from Science News on Vimeo. Video courtesy of NJ Vereecken.

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