Enhancing the trap of lady\u27s slippers: a new technique for discovering pollinators yields new data from Cypripedium parviflorum (Orchidaceae)

Approximately one-third of orchid species offer no reward to their floral visitors and instead trick them into pollination. Typically, these deceptive systems have low visitation and fruiting rates because pollinators can learn to avoid non-rewarding species. Consequently, pollination ecology studies in these species often require long hours in the field to witness relatively few floral visitations relative to rewarding plants. Cypripedium parviflorum is a food-deceptive orchid with a pouch-like trap that temporarily imprisons pollinators. To escape, pollinators exert pressure on the stigma which facilitates pollination and widens the escape holes located near each anther. This study reports the use of a ribbon and clip to block the escape passageway of this species in order to retain and observe visiting insects. The device was tested in a large population and was shown to increase significantly the probability of observing floral visitors by nearly three-fold. Ten species of hymenopteran visitors in the families Andrenidae, Apidae, Halictidae and Megachilidae were observed, with two female Adrena tridens and one male Adrena perplexa successfully removing pollen. Insect visitation to the orchids occurred during the first half of the flowering period and was significantly associated with warm, clear days. (C) 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160, 1-10