Orchid mantis' disguise lures prey
Pretty tricky A praying mantis that disguises itself as an orchid to catch prey has been shown to be more attractive to pollinators than real flowers, a new study shows.
The findings are published in The American Naturalist journal and confirm a long-held theory about the insect that dates back to the 19th century.
In 1879, Australian journalist James Hingsley returned from travels in Indonesia with tales of a carnivorous red orchid that engulfed butterflies in its petals and devoured them alive, says study lead author Dr James O'Hanlon, of the School of Biological Sciences at Sydney's Macquarie University.
However the 'red orchid' of Hingsley's tale was not a flower but a praying mantis, Hymenopus coronatus, "which has become renowned for its elusiveness and remarkable resemblance to a flower blossom," he says.
O'Hanlon says the belief the orchid mantis mimics a flower to attract insect pollinators as prey is assumed to be an established fact -- yet it has never been experimentally investigated.
He says the rarity of sightings of the insect in the wild has made it difficult to investigate the insect.
However in this study, O'Hanlon and colleagues used orchid mantises from private collections in Malaysia.
The insects were first studied using a spectrometer to compare the colours of the orchid mantis to those of flowers in areas it is known to inhabit.
"From the perspective of the pollinators," says O'Hanlon, "the colours of the flowers and the mantis overlap."
The insects were taken to a rainforest-based university field station outside Kuala Lumpur where orchid mantises are known to occur naturally.
The researchers placed five orchid mantises on sticks in different areas and left them alongside a native orchid and a bare stick.
More than 30 total hours of observation revealed the orchid mantis attracted the most attention with about eight visits by pollinators each hour, compared with six for the flower.
O'Hanlon says this could be explained by the mantis's use of "super stimulus".
"They [the mantis] are quite large and there are very few flowers that get to that size and they are quite a bit brighter than the surrounding flowers," O'Hanlon says.
This is the first documented case of floral mimicry occurring outside of flowering plants, the researchers say.
O'Hanlon says while other mantis species have mottled colouration to allow them to hide among flowers and twigs, the orchid mantis has moved along the evolutionary chain.
"The orchid mantis has gone one step further and become the flower itself," he says.
He suggests the rarity of the orchid mantises may be critical to their deception succeeding.
"Their rarity may ensure that the chances of pollinators encountering successive orchid mantises are low and reduce the likelihood that pollinators will learn to distinguish deceptive orchid mantises from rewarding flowers," he writes.