An Expert's View

Dr Rod Peakall is a professor at the department of Botany and Zoology, in the School of Biology at the Australian National University

Of all the extraordinary attributes of the orchid it is harder to think of one that tops the way some have evolved to deceive insects into pollinating them without the usual reward of nectar. “About one third resort to deception and offer their pollinator no rewards, I describe these species as naughty but nice, they are the cheats and liars of the plant world,” says Australian scientist Dr Rod Peakall.

Pollination by Sexual Deception

While different forms of deception are employed by these cheats of the plant world, most of these orchid falsely look and smell like flowers that would offer nectar. These orchids are thus visited by pollinators in search of food, but the pollinators do not find any. However, perhaps the most bizarre deceptive strategy employed by several hundred species of orchids is sexual deception.

In these cases, each species of these orchids emit a scent that mimics the pheromone of the female of their pollinator (typically a wasp or bee). Each orchid picks on a different species. Male wasps of the species are attracted to the orchid by this mimicry, attempt to mate with the flower, but only get pollen attached to their backs and then fly away disappointed. When they repeat the mistake at another flower it receives some of the pollen and pollination is complete.

“The remarkable thing is that the wasps are using these private communication channels for communication between male and female, yet the orchids have intercepted these channels and by so doing can lure the male pollinators to the flower,” Dr Peakall says.