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BROCHURE RACK

New species displays entirely new behaviour

12/01/2010 10:10:56
world/Asia/october_2009/cricket_pollinator

The raspy cricket (Glomeremus sp). The raspy cricket (Glomeremus sp)

First known instance of a cricket as an orchid pollinator captured on film by Kew scientist

February 2010. An orchid researcher, based on the island of Reunion in the Indian Ocean who is collaborating with researchers at the Royal Botanic Gardens in 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.

Cricket is new to science
Amazingly, not only is this the first time this behaviour has been documented in crickets (who are better known for eating plants), but the ‘raspy cricket' is also entirely new to science.

In 2008 Claire Micheneau, a RBG Kew-associated PhD student studying how an orchid 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.

Darwin study
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.

The raspy cricket (Glomeremus sp) carrying
pollen on its head.
(Credit: Michenau and Fournel)

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. So 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.

Usually pollinated by moths
"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."

Songbird pollination
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."

There is a close match in size between the raspy cricket's head and Angraecum cadetii's nectar-spur opening. 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."

The discovery was revealed in a paper published in Annals of Botany.

 

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