Biology Reference
In-Depth Information
the larvae. h ey evolved in concert to produce the adult phenotype.
Larvae produce a blend of carbon compounds called brood phero-
mone that inl uences foraging behavior and the feeding behavior of
nurses. It stimulates the development of the hypopharyngeal glands
(brood food glands) of nurse bees, and it delays the onset of foraging
in young bees, so more bees perform preforaging tasks, such as nurse
behavior. In colonies treated with supplemental synthetic brood pher-
omone, it increases pollen foraging, but not the amount of pollen stored,
so there is more pollen consumption and more protein available in the
brood food glands of nurse bees. h e result is an increase in the number
of larvae reared by the colony. Larvae provide signals to the nurses that
they are present in the cell and are hungry. Larvae also respond to the
nutritional delivery program provided by nurse bees, convert the nutri-
tional contributions of the nurse bees into tissues, and thereby may
control the investment in ovaries versus other body tissues. h erefore,
larvae af ect their development through their genetic-developmental
program and their ef ects on the nurse bees that feed them. We can
think of this as the “larval module” of development (Figure 8.4).
Nurse bees have evolved a developmental program that includes
their responses to the pheromonal signals and other cues derived from
the developing larvae, as well as the sizes of the cell in which the larvae
develop, that result in the quality, quantity, and temporal delivery of
food. h e responses of the larvae are matched to the program of the
nurses. For example, the nurses feed larvae ad lib during the i rst 2
days. Ad lib feeding during the i rst 2 days is probably a mechanism to
prevent starvation and death of the tiny larvae. During this time they
need a tremendous growth rate in order to reach the needed size and
weight within the 6-day window of larval development. h ey die rap-
idly when they run out of food. Older larvae are much more resistant to
starvation (unpublished data). Larvae may provide pheromonal signals
to inform nurse bees when they consume the food in their cells, stimu-
lating the nurses to replenish. h e nurses feed the worker larvae a diet
low in sugar, but the larvae must respond to lower sugar, perhaps by
eating less, and develop like a worker rather than a queen. At er 2 days,
workers receive restricted food from nurses but may increase their
