The relatively low bee activity in the pear orchards
under the Israeli conditions cannot be explained by the
"strength" (number of adult bee and brood area) of the
colonies. Free (1993) and Mayer et al. (1986)
recommended a minimum of 4–6 brood combs per
colony for apple and pear pollination, whereas in Israel
the minimum standard, as used in the present study, is
seven brood combs out of ten populated combs per
colony (Dag et al., 1999).

It seems that the main reason
for the relatively low bee activity was the competing
blooms surrounding the pear orchards in Israel.The pear
blooming season in Israel (March–April) is within the
peak of that of wild flowers (Zohary, 1962), whereas in
other countries with temperate climates, which grow
'Spadona', the wild flowers are only beginning to flower.
Thus, a high proportion of the bees from the colonies
introduced into the Israeli orchard forage outside in the
open fields

However, another reason for low bee activity on pear
is the low volume and the low sugar content in the
nectar (25% or less), which is below the threshold of
bee attractiveness to flowers (Vansell, 1946; Free, 1993;
Delaplane and Mayer, 2000).

-- 
Sequential introduction of honeybee colonies increases crosspollination,
fruit-set and yield of 'Spadona' pear (Pyrus communis L.)
By R. A. STERN et al
Journal of Horticultural Science & Biotechnology (2004) 79 (4) 652–658

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