Biology Reference
In-Depth Information
responsiveness. Some bees were narcotized with carbon dioxide or cold
temperature before they were placed in the tubes, while others served
as controls and were placed without narcosis. Bees were tested 30 and
60 minutes later. Bees that were narcotized were less responsive to su-
crose than the controls at 30 minutes, but the dif erences disappeared
by 60 minutes. Narcotized bees were shielded from the stress of han-
dling. Stressed bees became more responsive, probably because of ele-
vated levels of octopamine and juvenile hormone. Brain levels of octo-
pamine increase dramatically and rapidly with stress even when the
stress is simply the holding of a leg with forceps. Juvenile hormone ti-
ters also increase with stress, are known to be af ected by octopamine,
and af ect octopamine levels.
2.5.6 Links of the Sucrose-Response h reshold
to Other Sensory Modalities
Sucrose responsiveness correlates with other sensory modalities. h e
response to antennal stimulation with sucrose correlates with sucrose
stimulation of the mouthparts, but response thresholds to sugar pre-
sented at the antenna are 10 times higher than at the proboscis. Re-
sponses to sucrose based on antennal stimulation also correlate with
responses to citral (olfactory), pollen (gustatory), and light (visual).
h e relationship between sucrose sensitivity and response to light
has been best studied. Jochen Erber developed a light assay where bees
were placed in a dark, circular chamber. h ey remained for several
minutes before testing in order to adapt to darkness. h e chamber had
green-light-emitting diodes in a circle at the base that emitted light at
dif erent intensities (Figure 2.9). Lights of equal intensity opposed each
other on the circle. Lights were turned on individually, in increasing
intensity; each pair of lights of equal intensity doubled the intensity of
the previous pair. Activities of bees were recorded by using an infrared
light source and a video camera. One light of a given intensity was
turned on, and the time for the bee to walk to that light was recorded.
When the bee reached the light, it was turned of , the opposing light of
the same intensity was turned on, and the bee was timed and recorded
