INFLUENCE OF THE APETALOUS CHARACTER IN RAPE (BRASSICA-NAPUS) ON THE FORAGING BEHAVIOR OF HONEYBEES (APIS-MELLIFERA)

In order to establish whether commercial hybrid seed production betwee n petalous and apetalous rapeseed lines could be developed through ins ect cross-pollination, observations were made to compare the foraging behaviour of honeybees on both flower types with regard to their attra ctiveness. Number of flowers/m(2) and nectar volumes, considered as im portant attractive factors, did not differ between the two lines but n ectar sugar composition was slightly different. Honeybee density was s ignificantly higher on the apetalous line when their foraging activity was rather high. Honeybees showed a considerable constancy to each fl ower type. Passages between both types were not very frequent. Nectar foraging behaviour, observed under cages, differed with the floral mor phology. On the petalous flowers, honeybees visited the two inner nect aries by crawling over the anthers and the stigma, while on the apetal ous ones they often inserted their tongues between the sepals, thus ha ving less contact with the reproductive organs. From these results, th e honeybee efficiency in cross-pollination between petalous and apetal ous lines appears to be reduced.