SOIL ORGANISMS - Soil Ecology - page 320

associated musculature (Hölldobler and Wilson, 1990).
In addition to the physical and physiologically-defined castes and the other mor-
phologically-defined forms listed above, temporal castes occur that are defined on the
changing roles that they perform in the colony (temporal polyethism). For example, in
the myrmicine ant Pheidole dentata, the youngest minor workers (0-2 days) care prefer-
entially for the queen, the eggs and the youngest larvae. From 2 to 16 days, they care
for the medium-sized larvae. After this, they continue to work in the nest but an
increasing proportion of their time is spent in foraging outside the nest (Wilson, 1976).

4.3.3.3 Colony ontogeny

Ant colonies progress through a series of developmental stages analogous to those
occurring in the termites. There is an initial founding stage, followed by a period of
growth after which the colony achieves mature status, defined by the production of
reproductive forms. As occurs in all social insect societies, the colony eventually
declines and dies, often following the death of the founding queen and failure of other
workers or ergatogynes to take over the deceased queen's role. The colony may also be
destroyed at any stage through interactions with other ants, by predation, parasitism or
pathogenesis or as a consequence of other disturbance.
While colony establishment normally follows the liberation of virgin queens from the
parent nest, colonies may also establish through other swarming processes. This takes
place where a group of workers, sometimes with a queen, leaves the parent nest togeth-
er with one or more queens to establish a new colony.

The founding stage
Virgin emerging queens often leave the parent nest in response to a stimulus such as
rain and, after attracting a male and being inseminated, proceed to shed their wings and
establish their own nests. Following inital nest establishment, the queen produces her
first batch of eggs. In order to feed the developing brood, the queen supplies them with
trophic or non-fertile eggs, produced from the breakdown products of her fat bodies and
wing muscles. In some species, the queen remains in the nest and the first workers
are reared solely from the energy contained in her bodily secretions; this is known as
claustral founding. The situation in which she emerges periodically from the nest to
forage for food is known as partially-claustral founding.

The exponential, or ergonomic stage
This is the stage of colony growth. The workers produced from the initial brood are
known as minims and are usually smaller than those found later in colony development.
Subsequent to this, the queen devotes herself to egg production and the colony popula-
tion proceeds to increase over time in an approximately sigmoidal progression.

The reproductive stage
The stage of the mature colony is achieved when the population has started to approach
its asymptotic level. Brian (1957) has divided the reproductive stage into an adolescent
period during which only males are produced and the mature stage during which queens