Sequential introduction of honeybee colonies and doubling their density increases cross-pollination, fruit-set and yield in ‘Red Delicious’ apple

SummaryThe ‘Red Delicious’ apple exhibits full self-incompatibility, therefore its fruit production depends totally on cross pollination, especially by honeybees, which are the ultimate apple pollinators. In the present study, the technique of sequential introduction of honeybee colonies and doubling their density was applied to determine effects on yield. In three consecutive season it was found that sequentially increasing the density of colonies in the apple orchards from 2.5 colonies per ha., as recommended previously, to 5.0 colonies per ha, and introducing them sequentially (half at the 10% full bloom (FB) and half at FB), increased the number of bees per tree, their mobility among the rows, and the proportion of “topworkers” compared with “sideworkers” . It seems that a large number of foragers per tree directly increases the amount of pollination, high bee mobility between rows increases the amount of cross-pollination, and a high proportion of “topworkers” increases pollination efficiency. All the above effects were expressed in higher fruit set and higher yield (50–100%) in the treatment plots.