Biology Reference
In-Depth Information
5.4 Sensory- Response Systems
h roughout our studies of the ef ect of selection on the high- and low-
pollen-hoarding strains, we have conducted parallel studies using wild-
type bees. Studies of wild-type bees that were conducted in the labora-
tory of Jochen Erber of the Technical University of Berlin motivated us
to look at the same questions in the highs and lows. Studies of the high-
and low-strain bees in my lab motivated him to look for similar phe-
nomena in wild-type bees. h e end result has been the ability to gener-
alize our i ndings outside the context of our selectively bred bees.
5.4.1 Sensitivity to Sucrose
Our studies of the sensory-response systems in high- and low-strain
bees were motivated by experiments initially conducted in Erber's lab
when I was on sabbatical leave in 1996 (Section 2.5.2). We tested re-
turning pollen and nectar foragers from a colony of Carniolan bees
(Apis mellifera carnica)
for their proboscis extension response to water
and sucrose solutions and found that they dif ered signii cantly (Figure
2.7). We thought that they might dif er fundamentally, perhaps at the
level of the central nervous system, for their sensory perception and
response, but we did not know how to uncouple the experiential ef ects
of pollen and nectar foraging at er they had already initiated foraging,
so we had no way to know what they were “predisposed” to forage for
before they actually returned with a load. h e behavior itself might be
tuning sucrose responsiveness. h e high- and low-strain bees gave us a
tool to uncouple genetically determined biases from foraging experi-
ence because we had groups of bees that we knew had some level of ge-
netic predetermination to bias their foraging (Figure 5.8). h erefore, we
tested them.
5.4.1.1 High- and Low-Strain Bees and Sucrose Sensitivity
High-strain
bees are more responsive to water and more sensitive to sucrose than
are low-strain bees, which explains why high-strain foragers are more
likely to collect water and more dilute nectar. We tested high- and
