Production and composition of onion nectar and honey bee (Hymenoptera: Apidae) foraging activity in Arizona.

Nectar characteristics of six onion ( Allium cepa L.) cultivars were examined to assess the potential for preferential foraging by honey bees ( Apis mellifera L.). Mean nectar amounts for six cultivars ranged from 0.54 to 0.84 μl per floret per day. Onion cultivars differ in flowering potential, with cultivars varying from 176 to 359 flowers per umbel and 32 to 74 umbels per 30 onion plants. All cultivars examined contained highly concentrated nectar with total dissolved solids ranging from 52 to 65%. Onion nectar was analyzed by gas chromatography to determine qualitative sugar differences among onion cultivars. All cultivars were hexose-dominant, having sucrose ranges from 4.0 to 14.4% and nearly equal amounts of fructose and glucose. There were significant differences in sugar content between the onion cultivars. Nectar composition and honey bee visitation among the six test cultivars were compared. It was determined that honey bees foraged preferentially on some of the onion cultivars.