SUNFLOWER POLLINATION - ABUNDANCE, DIVERSITY AND SEASONALITY OF BEES AND THEIR EFFECT ON SEED YIELDS

Species (22) and/or groups of insects (mostly bees) were recorded visiting commercial sunflowers [Helianthus annuus var. macrocarpus (D.C.) (Ckll)]. Some bee species were abundant and present each season. Observations were made on the daily visitation pattern, amount of pollen carried on body hairs, behavior of bees during visitation, movement of pollen within the plots, nectar volume and sugar concentration, and effect of bees on seed yields. Data on oil seed content and seed germination were recorded. A discussion on management of native bees as potential pollinators of commercial sunflower plantings is presented, with special reference to the USA, where the work was done.