THE BEHAVIOR OF HONEY-BEES (APIS-MELLIFERA) VISITING AVOCADO (PERSEA-AMERICANA) FLOWERS AND THEIR CONTRIBUTION TO ITS POLLINATION

Observations of honey bee (Apis mellifera) foraging behaviour on five cultivars of avocado (Persea americana) were carried out in 1982-1984 and 1990-1992 in Galilee, Israel. Examination of the morphology of avo cado flowers showed that the pistillate and staminate flower stages ha ve similar structures. Bees collecting nectar, or nectar and pollen, v isited both pistillate and staminate flowers, and due to the flower st ructure they were forced to touch both pistil and anthers. Only limite d sites on a bee's body contacted the anthers, and these 'collection s ites' also contacted the stigma, which occupied the same position as t he anthers of the inner stamens. Most avocado pollen grains on bees vi siting staminate flowers were clumped at the 'collection sites' and co nstituted the main pollen available for pollination. Some pollen grain s randomly distributed over the entire bodies of bees visiting either pistillate or staminate flowers could have been acquired inside the hi ve, and did not play an important role in pollination. The observation s suggest that pollination within a cultivar is accomplished during th e overlapping phase of its pistillate and staminate flowering, during which bees collecting nectar and pollen move freely among neighbouring staminate and pistillate flowers. Pollination between cultivars of op posite flowering type is carried out by bees moving between them throu ghout the overlapping period of pistillate flowering of one cultivar a nd staminate flowering of the other. Bees which collect only pollen us ually do not visit pistillate flowers and do not contribute to pollina tion.