Pollination, foraging, and nesting ecology of the leaf cutting bee Megachile (Delomegachile) addenda (Hymenoptera: Megachilidae) on cranberry beds

The leaf-cutting bee Megachile addenda Cresson is an effective and potentially manageable pollinator of cultivated cranberries, Vaccinium macrocarpon Aiton. This facultatively gregarious, univoltine bee excavates shallow subterranean nests in the dikes and periodically flooded sand beds of commercial cranberries on southern New Jersey. Females provision 1-2 leaf-lined nest cells per day, each containing 3.9-5.4 million pollen tetrad (1992 and 1993 means, respectively) collected from a calculated minimum of 1,076-1,207 cranberry flowers. Using their middle and hind legs, pollen-foraging females repeatedly stroked in the 8 poricidal anthers of a virgin cranberry flower, removing 71% of the pollen while leaving an average stigmatic load of 28 tetrads (0.6% of pollen harvested). An estimated 1,291-1,440 berries should result from the daily foraging activity of a female, calculated using either pollen or time as currencies. In weather favorable for bee activity, and estimated 1,114 nesting females per hectare of cranberry bed could suffice to produce a commercial fruit set. Management of M. addenda for cranberry pollination must include control of its cleptoparasite Coelioxys immaculata Cockerell, which can parasitize >90% of nest cells when abundant.