Orthoptera, a new order of pollinator.
OBJECTIVE
Pollinator-mediated selection and evolution of floral traits have long fascinated evolutionary ecologists. No other plant family shows as wide a range of pollinator-linked floral forms as Orchidaceae. In spite of the large size of this model family and a long history of orchid pollination biology, the identity and specificity of most orchid pollinators remains inadequately studied, especially in the tropics where the family has undergone extensive diversification. Angraecum (Vandeae, Epidendroideae), a large genus of tropical Old World orchids renowned for their floral morphology specialized for hawkmoth pollination, has been a model system since the time of Darwin.


METHODS
The pollination biology of A. cadetii, an endemic species of the islands of Mauritius and Reunion (Mascarene Islands, Indian Ocean) displaying atypical flowers for the genus (white and medium-size, but short-spurred) was investigated. Natural pollinators were observed by means of hard-disk camcorders. Pollinator-linked floral traits, namely spur length, nectar volume and concentration and scent production were also investigated. Pollinator efficiency (pollen removal and deposition) and reproductive success (fruit set) were quantified in natural field conditions weekly during the 2003, 2004 and 2005 flowering seasons (January to March).


RESULTS
Angraecum cadetii is self-compatible but requires a pollinator to achieve fruit set. Only one pollinator species was observed, an undescribed species of raspy cricket (Gryllacrididae, Orthoptera). These crickets, which are nocturnal foragers, reached flowers by climbing up leaves of the orchid or jumping across from neighbouring plants and probed the most 'fresh-looking' flowers on each plant. Visits to flowers were relatively long (if compared with the behaviour of birds or hawkmoths), averaging 16.5 s with a maximum of 41.0 s. At the study site of La Plaine des Palmistes (Pandanus forest), 46.5 % of flowers had pollen removed and 27.5 % had pollinia deposited on stigmas. The proportion of flowers that set fruit ranged from 11.9 % to 43.4 %, depending of the sites sampled across the island.


CONCLUSIONS
Although orthopterans are well known for herbivory, this represents the first clearly supported case of orthopteran-mediated pollination in flowering plants.
Micheneau
Claire
C
Peuplements Végétaux et Bioagresseurs en Milieu Tropical, CIRAD-Université de La Réunion, 15 Avenue René Cassin BP 7151, 97715 Saint-Denis, La Réunion. claire.micheneau@univ-reunion.fr
Fournel
Jacques
J
Warren
Ben H
BH
Hugel
Sylvain
S
Gauvin-Bialecki
Anne
A
Pailler
Thierry
T
Strasberg
Dominique
D
Chase
Mark W
MW
D000818:Animals; D006135:Gryllidae / Q000145:classification / Q000502:physiology*; D019684:Magnoliopsida / Q000502:physiology*; D011058:Pollen