Ant, bee and fly pollination in Epipactis palustris (L.) Crantz (Orchidaceae)

In a semi-wild population in Haren, The Netherlands, Epipactis palustris (L.) Crantz was visited by honeybees, sawflies, parasitic hymenopterans, ants, hoverflies and other flies. Bumblebees rejected the flowers. Of the hoverflies only Lejogaster metallina and males of Syritta pipiens were pollinators. S. pipiens was common enough (20% of the visits) to effect substantial pollination. Small flies of several faimilies were effective pollinators but in low abundance (1%). Ants were the most frequent visitors (50%) and effected self- and cross-pollination. Honeybees (25%) pollinated and collected pollinia for larval food. Other hymenopterans were very rare on the flowers (1 %). Vespula vulgaris neglected the flowers. E. palustris was not autogamous here. The epichile bent down under heavy insects, and worked as a ‘springboard' for fight hymenopterans. On the epichile a taste nectar guide was found, effective for flies, ants, experienced honeybees and other hymenopterans.