Crickets found to pollinate plants

By Heather Catchpole 2 March 2010
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In a world first, a cricket is found helping a plant to reproduce.

For the first time a cricket – an animal that more often eats plants – has been caught on film acting as a plant pollinator.

The raspy cricket, a species of the genus Glomeremus previously unknown to science, is the curious pollinator of an orchid on the island of Reunion, in the Indian Ocean close to Mauritius.

The Angraecum orchid, which is more often pollinated by moths and birds, is famous for its role in proving Darwin’s theory that moths in Madagascar must have evolved tongues around 30 cm long to be able to penetrate the deep nectar-holding spurs.

Unusual pollinator

(Photo: KGB Kew)

Angraecum orchid

Claire Micheneau, a research student associated with the Royal Botanic Gardens in Kew, in London, England, and co-worker Jacques Fournel from the University of La Réunion, videoed the cricket’s night-time activity using motion sensitive cameras. The footage shows the cricket emerging with pollen on its head after visiting an orchid to feed on its nectar. (see video, below)

On Reunion, bird and cricket pollinators seemed to have evolved because of a lack of specific pollinators when the orchids colonised the island, Claire told Australian Geographic.

In 2005 she found two species of Angraecum orchids were pollinated by small white eye songbirds, but the pollinator of another species, A. cadetii, remained a mystery.

“We knew from monitoring pollen content in the flowers that pollination was taking place. However, we didn’t observe it during the day,” said Claire, who published her results about the cricket in a recent issue of the journal Annals of Botany.

“Watching the footage for the first time, and realising that we had filmed a truly surprising shift in the pollination of Angraecum, a genus that is mainly specialised for moth pollination, was thrilling.”

Sexual deception

Raspy crickets are opportunist foragers and may have developed a taste for nectar to compensate for a lack of other food resources, she added. The orchid may also be emitting a scent attractive to the cricket – orchids are well-known deceivers that employ a range of different strategies to attract pollinators.

For instance, an orchid discovered in China last year and described in the journal Current Biology emits a scent that mimics a distressed bee, thereby fooling its hornet pollinators into attacking the orchids’ flowers. In Australia, male wasps, ants and saw flies are among those deceived by the promise of a sexual reward by the pheromone-laden scents of particular orchids.

Evolutionary biologist Michael Whitehead, at the Australian National University in Canberra, is studying moths that mimic insects to trick them into pollinating them. He said he was impressed by Micheneau’s find. “To find a new order of pollinator is remarkable. It seems every year we find some new trick orchids are using to gain pollinators; they seem to be able to split off to find new, closely related species to exploit for pollinators.”