Bee visit rates vary with floral morphology among highbush blueberry cultivars (<i><scp>V</scp>accinium corymbosum </i><scp>L</scp>.)

Abstract

Abstract As the human population has increased, so too has the demand for biotically pollinated crops. B ees ( A poidea ) are essential for pollen transfer and fruit production in many crops, and their visit patterns can be influenced by floral morphology. Here, we considered the role of floral morphology on visit rates and behaviour of managed honey bees ( A pis mellifera ) and wild bumble bees (genus B ombus ), for four highbush blueberry cultivars ( V accinium corymbosum L .). We measured five floral traits for each cultivar, finding significant variation among cultivars. Corolla throat diameter may be the main morphological determinant of visit rates of honey bees, which is significantly higher on the wider flowers of cv. ‘Duke’ than on ‘ B luecrop’ or ‘ D raper’. Honey bees also visited cv. ‘Duke’ legitimately but were frequent nectar robbers on the long, narrow flowers of cv. ‘ B luecrop’. Bumble bees were infrequent (and absent on cv. ‘ D raper’) but all observed visits were legitimate. Crop yield was highest for the cultivar with the highest combined (honey bee + bumble bee) visit rate, suggesting that aspects of floral morphology that affect pollinator visit patterns should be considered in crop breeding initiatives.