Do honeybees promote or reduce the reproduction of two rare plants in Bulgaria?

Abstract. Two rare plant species protected by the Biodiversity Law – Astragalus dasyanthus and Haberlea rhodopensis – were observed, so as to list their flower visitors. The behaviour of the honeybees in close vicinity was recorded simultaneously. The aim was to test how they affect the pollination of these two plant species, presuming that honeybees may have neutral to negative impact on the pollination of rare plants. The observations revealed that honeybees preferred other plants for foraging in the studied communities. Since honeybees do not actually use A. dasyanthus and H. rhodopensis as foraging resources, they neither promote nor reduce the reproduction of these rare plants. Astragalus dasyanthus was actively visited by bumblebees – mainly Bombus hortorum and seldom by other bumblebee species, but not by honeybees. Honeybees were abundant in the vicinity but they collected food from Astragalus onobrychis, Dorycnium herbaceum, Onobrychis arenaria, Thymus sibthorpi,i and some other plants. Haberlea rhodopensis practically received no visits, except for a single nectar-collecting B. hortorum queen. In this study site honeybees were also very active but they pollinated Geranium macrorrhizum