Island found to host first known flower-pollinating cricket
Birds do it, bees do it, and apparently crickets do it too. Using night-vision cameras, scientists have documented cricket pollination of an orchid on the island of Réunion. The sighting is the first report of flower pollination by an orthopteran insect, a member of the order that includes katydids, grasshoppers and locusts, researchers report online January 11 and in an upcoming issue of the Annals of Botany. And the cricket itself — a species of raspy cricket — is new to science.
“This was very unexpected,” says study coauthor Claire Micheneau, a doctoral student at CIRAD–Université de La Réunion who collaborated with researchers from Royal Botanic Gardens, Kew in England. The find has left the scientists wondering if cricket pollination may be more widespread, yet was unseen because researchers hadn’t been looking for it. “The answer to a question brings us further questions,” Micheneau says.
To investigate the pollination strategy of the Angraecum cadetii orchid, Micheneau and her colleagues trained night cameras on the plants. The researchers were startled to see a cricket retreating from a flower, pollen coating its head. To make sure the event wasn’t a one-time wonder, the researchers recorded hours of footage, conducted pollination experiments and measured the crickets’ heads. The crickets were the only pollinator the team observed on that type of orchid. Crickets accessed the flowers by climbing up leaves or jumping from plant to plant, the researchers report.
Interactions with bees, birds and butterflies aren’t unusual for flowering plants, but every now and then a new pollinating face emerges. In recent years scientists have reported flower pollination by cockroaches and even lizards. These oddball partnerships can arise when a plant disperses beyond the range of its original pollinator, says W. Scott Armbruster of the University of Alaska in Fairbanks, who was not involved in the research. In this instance, A. cadetii — a relative of a famously long-spurred orchid that Darwin studied — probably migrated from nearby Madagascar.
Both the cricket — a new species in the genus Glomeremus — and the orchid appear to have been prepared for the partnership, the scientists note. The cricket belongs to a family with members that return to a nest each night, and thus has the memory and navigation skills that would help the cricket find and return to the orchid booty, the researchers say. As for the orchid, A. cadetii and its closest relatives are creamy white and give off scent at night, and hence would be noticeable to such nocturnal hunters as crickets. Compared with that of distant relatives, the nectar spur of closely related orchids is also a bit wider and so better able to accommodate a big cricket. It wouldn’t have taken much for natural selection to drive the spur to widen even further in A. cadetii, Armbruster notes.
“The deck becomes stacked for these relationships to develop,” he says. “It was the right orchid and the right cricket.”
Finding an entirely new plant–pollinator interaction illustrates the tight connections among species, notes Armbruster. “We tend to think of biodiversity in terms of lists of species, but it is actually lists of interactions.” Preserving an endangered plant doesn’t do much good unless its pollinator is protected too, he says.
The research raises several questions, including what’s in the orchid’s nectar. Nectar is often thought of as empty calories compared with protein-rich pollen. An analysis of this orchid’s nectar may shed further light on why this cricket took the plunge.
A new species of raspy cricket is caught on film pollinating the Reunion island orchid Angraecum cadetii. It is the first documented instance of flower pollination by a cricket.
Video credit: Micheneau and Fournel
Claire Micheneau, Jacques Fournel, Ben H. Warren, Sylvain Hugel, Anne Gauvin-Bialecki, Thierry Pailler, Dominique Strasberg and Mark W. Chase. 2010. Orthoptera, a new order of pollinator. Annals of Botany Online ahead of print