Ant Encounters by Gordon Deborah

Author:Gordon, Deborah [Gordon, Deborah]
Language: eng
Format: epub
Tags: 9780691138794
ISBN: 9780691138794
Published: 2010-09-03T09:00:42+00:00

colony size

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nesting space for the ants. Often, they also feed the ants, either

directly through nectar bodies or indirectly by providing

resources for scale insects that suck the phloem of the plant

and excrete a sugary solution that feeds the ants. In turn, the

ants defend the plant from herbivores. By protecting the host

plant, the ants promote its growth. Larger colonies provide

more effective defense, so as the colony grows, it helps the

plant to grow more nest sites. This in turn allows the colony

to grow more, because a larger plant provides both more nest-

ing space for the ants and more resources for the scale insects

that feed the ants. Thus, as Megan Frederickson has shown in

studies of Amazonian ants and their host plants,8 the growth

of a colony fuels further growth. This is not only because, as

in any ant species, a larger colony has more ants to obtain

more resources, but also because a larger colony actually pro-

duces more resources for itself, by promoting the growth of

its host plant.

Task Allocation and Colony Size

As colonies grow, there is a shift in the allocation of workers

to various tasks. There are data on this for only a few species,

but these all show that a higher proportion of the colony is

devoted to foraging when the colony is young and small than

when it is older and larger. The result is that the total number

of foragers does not increase linearly with colony size. For

example, counts made of foragers outside the nest show that

in a young harvester ant colony with 1,000 ants, about 500,

or 50%, are foragers; in an old colony with 10,000 ants, about

2,000, or 20%, are foragers. The 4-fold increase in number of

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