Study reveals a new means by which plants can deceive their pollinators.
Some flowers are masters of deception. Such is the case for an ornamental flower called the Giant Ceropegia, which produces a scent mimicking that of honeybees under attack to lure in pollinating flies looking to feast on dead honeybees.
The flies, known as Desmometopa, are carnivorous, often feeding on honeybees that have been preyed upon by spiders. To find their meals, the flies cue in to the volatile compounds that the bees release in their venom after being attacked, which are intended to call nest-mates over for help.
Stefan Dötterl of the University of Salzburg in Austria and his colleagues analyzed these defensive compounds by squeezing and poking honeybees to simulate at attack, and then collecting their venom.
Then, noting how the same flies that were attracted to the honeybee-released compounds also appeared to be drawn to the alluring aroma of the Giant Ceropegia flowers, the researchers extracted chemicals released by the plant for comparison.
They found that the flowers engaged in false advertising — their floral scent was highly similar, in terms of chemical composition, to the honeybee venom. In fact, the two shared a unique mixture of four compounds.
An experiment revealed that the flies were able to perceive many of the compounds shared by the flowers and honeybee venom, and that they preferred to spend time at vials containing blends of these compounds, rather than control vials filled with acetone.
“They really look for a combination of compounds,” Dötterl tells New Scientist, adding that the team “found no other organism, other than the honeybee and this flower, which releases all four compounds together.”
“Chemical mimicry is often used as an efficient way to exploit the olfactory preferences of animals for the purpose of attracting them as pollinators,” the researchers write in the journal Current Biology. The Giant Ceropegia’s floral scent is “a new example of how a plant can achieve pollination through chemical mimicry of the food sources of adult carnivorous animals.”
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