A specialised pollination system using nectar-seeking thynnine wasps in Caladenia nobilis (Orchidaceae).

Abstract in brief

• This study investigated how the Caladenia nobilis orchid is pollinated, focusing on whether it uses a food deception system or offers nectar rewards, and found that it predominantly attracts male thynnine wasps (Rhagigaster discrepans) that attempt to feed but do not get a nectar reward.
• The flowers produced little to no nectar and had color similarities to orchids pollinated by sexual deception, although C. nobilis had a lighter-colored labellum, suggesting a possible intermediate pollination strategy between food deception and reward.
• Reproductive success was low and variable, with many insect visitors being unsuitable for pollination, and the study raises the idea that some orchids thought to be rewardless may actually produce tiny amounts of nectar attracting certain pollinators.]