Nectar Robbery by Bees Xylocopa virginica and Apis mellifera Contributes to the Pollination of Rabbiteye Blueberry

Blair J. Sampson, Robert G. Danka, Stephen J. Stringer
2004 Journal of Economic Entomology  
Honey bees, Apis mellifera L., probe for nectar from robbery slits previously made by male carpenter bees, Xylocopa virginica (L.), at the ßowers of rabbiteye blueberry, Vaccinium ashei Reade. This relationship between primary nectar robbers (carpenter bees) and secondary nectar thieves (honey bees) is poorly understood but seemingly unfavorable for V. ashei pollination. We designed two studies to measure the impact of nectar robbers on V. ashei pollination. First, counting the amount of pollen
more » ... on stigmas (stigmatic pollen loading) showed that nectar robbers delivered fewer blueberry tetrads per stigma after single ßoral visits than did our benchmark pollinator, the southeastern blueberry bee, Habropoda laboriosa (F.), a recognized effective pollinator of blueberries. Increasing numbers of ßoral visits by carpenter bee and honey bee robbers yielded larger stigmatic loads. As few as three robbery visits were equivalent to one legitimate visit by a pollen-collecting H. laboriosa female. More than three robbery visits per ßower slightly depressed stigmatic pollen loads. In our second study, a survey of 10 commercial blueberry farms demonstrated that corolla slitting by carpenter bees (i.e., robbery) has no appreciable affect on overall V. ashei fruit set. Our observations demonstrate male carpenter bees are benign or even potentially beneÞcial ßoral visitors of V. ashei. Their robbery of blueberry ßowers in the southeast may attract more honey bee pollinators to the crop.
doi:10.1603/0022-0493(2004)097[0735:nrbbxv];2 pmid:15279245 fatcat:nmqlk6tmqfg45mahz6wirdeqji