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of a day of foraging life. As a consequence, low-strain bees live longer
than high-strain bees because they initiate foraging later.
5.3.2 Foraging Bias
Nectar and pollen loads are not independent. High-strain foragers
collect relatively larger loads of pollen and smaller loads of nectar,
so pollen is a relatively higher proportion of their total loads. High-
and low-strain bees do not dif er in the l oral types of pollen they col-
lect. High-strain bees are more likely to collect water and under
poorer foraging conditions are more likely to return with loads of nec-
tar that are more dilute, while low-strain bees are more likely to return
empty.
As we found for the pollen-hoarding trait, pollen-foraging bias shows
directional dominance for low pollen bias, with the low strain more
similar to the wild-type bees. Relatively more high-strain bees collect
only pollen, and more low-strain bees collect only nectar, but many
collect both (Figure 5.7). Hybrid workers derived from crossing high-
and low-strain queens and drones show an even stronger bias for nec-
tar than the low-strain workers, corresponding to the greater amount
of stored honey found for hybrid colonies. High- and low-strain bees
respond to changes in the nest stimulus environment. Both collect
more pollen and forage at younger ages under the high-pollen-foraging
stimulus of high quantities of young larvae and low stored pollen. How-
ever, high-strain bees are more sensitive to the pollen-foraging stimuli
and more readily change their foraging behavior in response to changes
in brood and stored-pollen stimuli. High-strain bees are less likely to
return empty from a foraging trip. Wild-type bees are intermediate in
foraging behavior.
Potential foragers (recruits) may be biased to attend recruitment
dances and get information from pollen or nectar foragers. If this is
the case, it could explain some of the tendency for high-strain bees to
forage for pollen and low-strain bees to forage for nectar. Claudia
Dreller marked a large number of high- and low-strain bees and put
them in an observation hive where she could observe their behavior
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