Biology Reference
In-Depth Information
cally based mechanism underlying changes in nest location and task
per for mance.
Other studies likewise show that there are genetic and physiological
factors that move worker honey bees through sets of tasks and hive lo-
cation. Kim Fondrk and I selectively bred two distinct populations of
bees that dif er dramatically in the amount of pollen they store in the
comb and in their foraging behavior (Chapter 5). We called them the
high- and low-pollen-hoarding strains. When high- and low-strain
workers are raised together in the same hive at the same time, the high-
strain bees forage about 10 to 12 days earlier in life, pass through all the
task transitions when they are younger, and spend less time engaged in
each task (Adam Siegel and Robert Page, unpublished data). h e transi-
tion from working in the nest to foraging is marked by a dramatic de-
crease in blood-circulating vitellogenin (a precursor of egg-yolk pro-
teins in insects in general and a protein involved in the regulation of
behavior in honey bees) and a concomitant increase in circulating juve-
nile hormone (Chapter 7). When bees are treated with an analog of ju-
venile hormone, they pass through the behavioral transitions faster
and forage earlier in life. h e same is true when the gene that makes
vitellogenin is silenced. h ese results demonstrate that juvenile hor-
mone and vitellogenin are physiological drivers of locational and be-
havioral changes.
We can conclude that temporally patterned physiological changes
take place in workers as they age and move to dif erent places in the
nest, where they encounter and respond to dif erent stimulus environ-
ments. In addition, their responsiveness to stimuli changes. We assume
that they are “tuned” to the relevant stimuli in those locations and that
the tuning subsequently af ects division of labor. However, the rates at
which they change location and tasks vary with the colony environ-
ment, and even the direction of change can be reversed.
2.5.10 Connectedness Is Not Constant, and
K
Does Not Equal
N
Returning nectar foragers pass their loads to primary receivers, who in
turn pass some of their load to secondary receivers (primary receivers
