First known instance of a cricket as an orchid pollinator captured on film by Kew scientist
An orchid researcher based on the island of Reunion in the Indian Ocean, and collaborating with researchers at Kew, has used motion-sensitive night cameras to capture the first known occurrence of a cricket functioning as a pollinator of flowering plants.
In 2008, Claire Micheneau, a Kew-associated PhD student studying how the epiphytic orchid genus Angraecum has adapted to different pollinators on Reunion Island, and Jacques Fournel, her collaborator, shot this remarkable footage. It shows a 'raspy cricket' (Glomeremus sp.) carrying pollen on its head as it retreats from the greenish-white flowers of Angraecum cadetii.
The genus Angraecum is best known for Darwin’s study of the Christmas star orchid (Angraecum sesquipedale) of Madagascar, and his hypothesis that it was pollinated by a bizarre, long-tongued moth pollinator – a theory that was proved to be true many years after his death.
The moths that are the main Angraecum pollinators on Madagascar are not found on Reunion, and until we started our research the pollination of this genus on Reunion had always been an open question.
Watch this unique footage
Claire talks about the importance of this discovery
Talking about the discovery, Claire Micheneau said:
'We knew from monitoring pollen content in the flowers that pollination was taking place. 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 that we had filmed a truly surprising shift in the pollination of Angraecum, a genus that is mainly specialised for moth pollination, was thrilling.'
Micheneau’s research also revealed that two other species of Reunion Island Angraecum orchids (A. bracteosum and A. striatum) are pollinated by two species of small white eye songbirds (Zosterops borbonicus and Zosterops olivaceus).
'My studies have shown that the raspy cricket is also a surprisingly efficient pollinator with higher rates of pollination and fruit set in Angraecum cadetii than those recorded in its bird-pollinated sister-species.'
There is a close match in size between the raspy cricket’s head and Angraecum cadetii’s nectar-spur opening. A nectar spur is a hollow tube extending from the petals of a flower that holds nectar in its base. These wingless raspy crickets reach the flowers by climbing up the leaves of the orchid or jumping across from neighbouring plants. They use very long antenna to explore their surroundings.
A question remains
Just why the raspy cricket developed a taste for orchid nectar is still a key question for Micheneau. 'Although crickets are typically omnivorous and eat both plant material and other insects, we think the raspy cricket has evolved to eat nectar to compensate for the general scarcity of other insects on Reunion.'
It is thought the raspy cricket gets its name from the sound it makes by rubbing its legs together to try to scare off enemies.