THE POLLINATION OF 'DELICIOUS' APPLE BY APIS MELLIFERA L. AND MEGACHILID BEES OF THE GENUS OSMIA

"Sideworking" is a foraging behavior of honey bees (Apis mellifera L.) commonly seen on 'Delicious' blossoms where the honey bees forage for nectar by standing on the petals of the blossoms while forcing their proboscises through the stamens. As a result, the honey bees usually do not contact the blossom's anthers and pollen transfer is unlikely. The structure of a 'Golden Delicious' blossom, a commonly used pollinizer of 'Delicious', also permits "sideworking" behavior by honey bees under certain conditions. In orchards of 'Golden Delicious' and 'Delicious' cultivars where 'Delicious' bloomed slightly ahead of 'Golden Delicious', the percentage of honey bees working from the side of the blossoms of 'Golden Delicious' was initially greater than 50% but decreased to less than 20% as the bloom of 'Golden Delicious' advanced. This decrease in sideworking behavior by honey bees on 'Golden Delicious' was believed to be due to the earlier bloom of 'Delicious' cultivar and its effect on honey bee foraging behavior.;Preliminary experiments showed that when the cultivar 'Limbertwig' was used as a pollinizer the number of blossoms that set fruit increased by 6-10%, fruit yield increased by 23%, the total number of viable seeds in fruit increased by 26% and fruit shape improved.;In areas of orchards where megachilid bees of the Genus Osmia nested, results indicated that initial fruit set of 'Delicious' blossoms increased by as much as 54%, the total number of viable seeds in fruit increased by as much as 44%, the number of carpels with viable seeds in fruit increased by as much as 39%, and fruit shape was improved as compared to those areas which lacked nesting Osmia even if honey bees were present.;In an orchard composed completely of 'Golden Delicious', 'Delicious' influences on honey bee foraging behavior were absent and the percentage of honey bees "sideworking" 'Golden Delicious' blossoms remained below 30%. A preponderance of "sideworking" honey bees on the pollinizer 'Golden Delicious' during the period in which the blossoms of 'Delicious' optimally set fruit might have a negative effect on fruit shape or fruit set or both of 'Delicious' apple.