Biology Reference
In-Depth Information
until it reached the light at the opposite side. At er a set number of
back-and-forth trips, paired lights of the next-higher intensity were
used. If bees did not respond to a given light intensity at er a set
amount of time, the next-higher light intensity was used. Erber and
his colleagues found that nectar and water foragers with higher re-
sponsiveness (lower response thresholds) to sucrose were also more
sensitive to light. Jennifer Tsuruda tested young, nonforaging bees for
their sucrose-response thresholds and then used this apparatus to test
them for their responses to light. Foragers that responded to lower
concentrations of sucrose solution also responded to lower light inten-
sities. She found a signii cant correlation between sucrose and light
responses.
2.5.7 Responses Are Analog
Our stone-soup model assumes a Boolean-binary logic (Section 2.2).
Decision functions deliver an on or of result along directed arrows
to connected nodes. h e logic of the “spirit of the hive” is probably
analog (continuous) with suprathreshold responses. In other words,
responses vary in intensity with increases in stimulus levels above
thresholds.
2.5.7.1 Proboscis Extension
Suprathreshold responses are shown at the
most elementary level by looking at the proboscis extension response
(Figure 2.7). Bees whose antennae are stimulated with sucrose solution
frequently only partially extend their proboscis. For the next-higher
concentration they may extend it more slowly, then faster for the con-
centration that follows. Stephan Haupt, working in the laboratory of
Jochen Erber, recorded electrical impulses from a single muscle used
by the bee when she extends her proboscis. h e number of electrical
impulses per second increased linearly with the concentration of sucrose-
solution stimulation of the antenna. Merideth Humphries showed that
the walking speed of newly emerged honey bees correlates with sucrose
responsiveness. Bees that are more sensitive to sugar walk faster. h
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