Pollinator biodiversity and floral resource use in Ecballium elaterium (Cucurbitaceae), a Mediterranean endemic

Abstract

Pollinator biodiversity on Ecballium elaterium (L.) A. Richard was studied for 2 years at 2 sites in southern France. Six families, 15 genera, and 43 species of bees were collected from the flowers, and 33 bee species carried Ecballium pollen in their scopae. The numerically dominant species were Lasioglossum malachurum (Kirby), the honey bee, Apis mellifera L., and Ceratina cyanea (Kirby). Few pollinators were observed in 1997 due to a drought. In 1996, mean forager density was slightly over one bee per 100 flowers throughout the flowering period. Most visitors (98%) were female bees which foraged for both pollen and nectar. Most visits (97%) were to staminate flowers and visitation to pistillate flowers was by deceit since these are nectarless. Behavior of nectar foragers on staminate flowers differed according to body size. Large bees foraged for nectar mostly in the afternoon after nectar sugar concentrations reached high values while smaller bees foraged for nectar throughout the day.