Nectar sugar production and honeybee foraging activity in 3 species of onion (Allium species)

Abstract - Nectar sugar content and solute concentration in the nectar of 3 Allium species were determined to assess their potential for honeybee foraging. The pattern of nectar secretion varied among the 3 onion species. In A cepa and A cepa fistulosum there was resorption of nectar sugars after 72 and 144 h of flower opening, whereas in A fistulosum even 144-h-old flowers contained 3.908 mg sugar/flower and there was no apparent resorption. The 3 onion species contained highly concentrated nectar and the solute contents were on average 68.96, 56.74 and 53.47% in A cepa, A fistulosum and A cepa fistulosum, respectively. The 24-h sugar value varied between 0.219 to 0.767 mg/flower, though significant amounts of sugar were produced after this period. Honeybees preferred the nectar of A cepa. Among honeybees, Apis dorsata dominated the blooms as compared to A mellifera and A cerana indica. The differential preference of A cepa by honeybees might be associated with the concentration of nectar solutes coupled with the amount of dry nectar sugars.