Orchid wears the scent of death to attract flies for pollination.
The orchid S. pumilum is found in sandy, moist conditions near small streams across the Cape floral kingdom of South Africa.
The flowers are a puzzle. They don't carry any nectar and even if they did, the spurs that would hold it are the wrong shape to feed any visitors. So it has been a question about how they attract insects to pollinate their flowers.
"We know it's common for orchids to deceive insects into pollinating them. We also know that some plant species can mimic carrion to attract flies. What we didn't know was how successful this was. Mimicry is often a very poor way to pollinate a plant. So we set out to observe the plants in the wild and see if we could work out how they were attracting flies," said Timotheus van der Niet at the University of KwaZulu-Natal, lead author.
The team staked out a region of farmland with many of the orchids on it. They then went about finding carrion for a comparison.
"We didn't kill creatures to entice the flies. Instead we used dassies (rock hyraxes). They're small animals and they look a little like a guinea pig. You can find them almost anywhere in South Africa, and that means you can also find them as roadkill. So we examined the flies visiting the dead dassies, and compared them to the flies visiting the orchids," said Van der Niet.
"Because of the high density of orchids we didn't see many flies visiting the flowers, but on the nearby dassie carcass we caught a lot of flies carrying orchid pollen, providing ample 'smoking gun' evidence of how common this interaction was.
"However, we found that not every species of carrion fly at the dassie carcass had orchid pollen on it. The ones that were carrying the pollen were flesh-flies, mostly females," he added.
Further experiments on the flowers showed that the orchids were mimicking the smell of small amounts of carrion. Studies on flies have shown that flesh-flies are better at finding these food sources than other flies. (ANI)
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|Publication:||Asian News International|
|Date:||Mar 16, 2011|
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