Grasshoppers and their relatives can pollinate plants like bees, scientists have discovered.
The unexpected finding has come from the island of Réunion in the Indian Ocean, where a cricket has been seen pollinating an orchid – that is, transferring pollen, which contains a plant's male sperm, to another plant's female organs, enabling it to produce seeds.
Crickets, like most members of the insect order Orthoptera (grasshoppers and their allies), are well-known for eating plants rather than helping them to reproduce. Until now, the insects known to be involved in pollination, with honey bees leading the way, have included ants, beetles, hoverflies, butterflies and moths, while birds and even bats can be involved in the pollination process – but no crickets or grasshoppers.
The unprecedented behaviour was recorded on a nocturnal camera set up by orchid researcher Claire Micheneau in a Réunion cloud forest, which caught a raspy cricket in the act of pollinating a species of epiphytic, or tree-growing, orchid called Angraecum cadetii.
"We knew from monitoring pollen content in the flowers that pollination was taking place," said Dr Micheneau, who is collaborating with the Royal Botanic Gardens, Kew. "However, we did not observe it during the day. That's why we rigged up a night camera and caught this raspy cricket in action.
"Watching the footage for the first time, and realising we had filmed a truly surprising shift in the pollination of Angraecum, a genus that is mainly specialised for moth pollination, was thrilling."
The green-and-white flower is closely related to the comet orchid of Madagascar, which Charles Darwin famously theorised would be pollinated, because of the plant's long nectar spur, or tube, by a moth with an enormously long proboscis. Years after Darwin's death, this was shown to be right – the pollinator proved to be a hawk moth with a proboscis 14in (35cm) long.
On Réunion the moth does not exist, so scientists think that the island's three species of Angraecum orchids, which originated in Madagascar, have reversed their evolution and developed a shorter nectar tube which can be used by other insects, such as the raspy cricket.
Dr Micheneau's discovery was published yesterday in the journal Annals of Botany. The footage from the motion-sensitive night camera, which she set up with her colleague Jacques Fournel, shows the raspy cricket carrying pollen on its head as it retreats from the orchid flowers. There is a close match in size between the raspy cricket's head and Angraecum cadetii's nectar-spur opening.
The wingless raspy cricket reaches the flowers by climbing up the leaves of the orchid or jumping across from neighbouring plants.