An orchid researcher based on the island of Reunion in the Indian Ocean and collaborating with researchers at the Royal Botanic Gardens, Kew (RBG Kew) has used motion sensitive night cameras to capture the first known occurrence of a cricket functioning as a pollinator of flowering plants. Not only is this the first time this behaviour has been documented in a member of the Orthoptera order of insects - who are better known for eating plants - but the 'raspy cricket' is also entirely new to science. The discovery is revealed in a paper published today (12 January 2010) in Annals of Botany.
In 2008 Claire Micheneau, a RBG 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 the 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 comet orchid, Angraecum sesquipedale of Madagascar, and his hypothesis that it was pollinated by a bizarre, long-tongued moth pollinator - a theory that was later proved to be true many years after his death.
Says Claire Micheneau, "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.
"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."
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).
She continues, "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." (1)
There is a close match in size between the raspy cricket's head and Angraecum cadetii's nectar-spur opening (2). These wingless raspy crickets reach the flowers by climbing up the leaves of the orchid or jumping across from neighbouring plants. They use long very long antenna to explore their surroundings.
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."
Claire Micheneau and Professor Mark Chase, Keeper of the Jodrell Laboratory and a co-author of the paper, are available for interview. Please contact the Royal Botanic Gardens, Kew press office on firstname.lastname@example.org or +44 (0)20 8332 5605
Film footage of the cricket can be downloaded here
Please contact the Royal Botanic Gardens, Kew press office for the user name and password
Images are available to download from www.kew.org/press/images Please contact the Royal Botanic Gardens, Kew press office for the user name and password
A PDF of Orthoptera, a new insect order recorded as orchid pollinator (DOI 10.1093/aob/mcp299), is available from the Royal Botanic Gardens, Kew press office www.aob.oxfordjournals.org
Notes to editors
(1) Fruit set was 10% for the bird-pollinated species, and around 20% for Angraecum cadetii
(2) A nectar spur is a hollow tube extending from the petals of a flower that holds nectar in its base
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
The Royal Botanic Gardens, Kew is a world famous scientific organisation, internationally respected for its outstanding living collection of plants and world-class Herbarium as well as its scientific expertise in plant diversity, conservation and sustainable development in the UK and around the world. Kew Gardens is a major international visitor attraction. Its landscaped, 132 hectares and RBG Kew's country estate, Wakehurst Place, attract nearly 2 million visitors every year. Kew was made a UNESCO World Heritage Site in July 2003 and celebrates its 250th anniversary in 2009. For further information please visit www.kew.org.
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Investigating plant characteristics and relationships at a molecular level to help plant conservation;
Using DNA finger printing techniques to study the genetics of endangered species;
Improving and re-evaluating our understanding of the interrelationships between flowering plants using genetic studies;
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Identifying and describing new families, genera and species of fungi in the UK and overseas.
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