Flowers Trick Prey with Scent

Some orchids are exquisite cheats: instead of offering a nectar reward to their pollinators, they trick insects into alighting on their flowers by simulating the shape, color, or odor of potential mates. The great variety in orchid deception has been known for a long time, yet new examples keep turning up.

Take the orchid Dendrobium sinense. Restricted to the Chinese island of Hainan, the species has lovely white flowers with red centers. A team, led by Jennifer Brodmann and her graduate adviser Manfred Ayasse of the University of Ulm in Germany, observed the hornet Vespa bicolor regularly visiting the flowers, pollinating them inadvertently in the process. The hornets didn’t just drop in casually on the flowers, however; they pounced on the red centers with the same vigor they exert hunting honeybees to feed to their larvae. In a series of experiments, the team established that the flowers produce a volatile compound also made by honeybees, which is what attracts the hornets. Normally, the hornets cue in on the compound to locate victims.

Some orchids imitate the shape of a pollinator’s prey—the genus Brassia bears spider-shaped flowers pollinated by spider-parasitizing wasps—but D. sinense is the first known to mimic a prey’s scent.

This reasearch was detailed in the Journal Current Biology.

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