Nectar-Robbing Carpenter Bees Reduce Seed-Setting Capability of Honey Bees (Hymenoptera: Apidae) in Rabbiteye Blueberry,Vaccinium ashei, ‘Climax’

Abstract

The carpenter bee, Xylocopa virginica (L.), acts as a primary nectar thief in southeastern plantations of native rabbiteye blueberry, Vaccinium ashei Reade, perforating corollae laterally to imbibe nectar. Honey bees, Apis mellifera L., learn to collect nectar from these perforations and thus become secondary thieves. We conducted a 2-yr study to assess how nectar robbing in honey bees affects fruit production in rabbiteye blueberry. Various harvest parameters were measured from fruit collected from plants tented with honey bees and carpenter bees (AX), carpenter bees (X), honey bees (A), no bees (0), or in open plots (open). In open plots, rates of illegitimate honey bee flower visitation increase from initial lows to fixation at ≥95%. Fruit set is higher in open, A, and AX plots than in X and 0 plots. Even though fruit set is similar in A and AX plots, seed numbers are significantly reduced in AX plots in which X. virginica-induced illegitimate honey bee flower visitation approaches 40%. Open-pollinated berries were larger than berries from all other treatments in 2001, whereas in 2002 berry weight followed the pattern A > open > AX > (X ≈ 0). Sucrose content of juice and speed of ripening were unaffected by treatments.