Biology Reference
In-Depth Information
5.6 Nonassociative Learning
High- and low-strain bees also dif er for elements of nonassociative
learning. Nonassociative learning can take the form of sensitization or
habituation. Sensitization occurs when a bee exhibits increased respon-
siveness following exposure to a strong stimulus. h is is demonstrated
when a bee that has been stimulated with a high-sucrose solution re-
sponds to a low-sucrose concentration that she would not respond to
before the strong stimulus. A decline in response with repeated, unre-
warded stimulation is habituation. For example, a bee that is repeatedly
stimulated with water or a low-sucrose concentration gradually ceases
to respond. Not only does sensitivity to sugar af ect associative learn-
ing, but it also has an ef ect on nonassociative learning.
Vasantha Kolavennu worked in my lab in 1999 as a high-school in-
tern and performed some very nice experiments demonstrating that
newly emerged high- and low-strain bees dif er in their sucrose-response
thresholds and that response thresholds correlate with sensitization and
habituation (unpublished results). In the i rst experiment, Kolavennu
tested whether high- and low-strain bees dif er in their responses to
water and sucrose solutions when they are newly emerged, before
they have social or foraging experiences. Responsiveness was mea-
sured as total gustatory responses (gustatory response score, GRS) for
the seven solutions tested (water plus six sucrose solutions). h us, a
higher GRS signii es a lower response threshold (RT), while a lower
GRS signii es a higher RT (Figure 2.7). h ere was a signii cant dif er-
ence in the GRSs of newly emerged low- and high-strain bees; high-
strain bees were signii cantly more responsive. h is is interesting
because the bees were just 4 hours old but already demonstrated dif er-
ences in their sensory responses that correlated with foraging behavior
weeks later.
Next, Kolavennu tested bees for their level of sensitization and resis-
tance to habituation. At er i nal stimulation with 30 percent sucrose so-
lution, bees were presented with 10 trials of pure water to see how long
they would continue to respond at er being sensitized. Previous studies
with Jochen Erber had shown that bees could be sensitized to respond to
