Pollination of Serapias vomeracea Briq. (Orchidaceae) by imitation of holes for sleeping solitary male bees (Hymenoptera)

In two locations in Israel, bees were found to be sleeping in flowers of Serapias vomeracea Briq. Of these bees. Proposis spp. and Ceratina spp. were too small to be pollinators, whereas Eucera spp., Andrena spp., Osmia spp. and Tetralonia spp., mostly males, pollinated. Pollination occurs when in the afternoon hours the bees waver from flower to flower. The bees finally come to rest on a particular flower and remain there for the duration of the night. In the morning, the bees which slept in the flowers, are warmed up as a result of solar radiation which heats the flowers to 3°C above ambient temperature. Since the males of many Hymenoptera sleep in holes, the hypothesis is that the flowers mimic such holes. The shortness of the flower tube can be held responsible for the observed frequent changes from flower to flower, which is so important for pollination efficiency.