colony units of fire ants standardized by worker number, 8 competition pairs of crazy ant
and fire ant colony units standardized by biomass, and 8 competition pairs of crazy ants
and fire ants standardized by worker number.
For all but two units, the queen and the workers came from the same source
colony. The two exceptions were crazy ant units from a source colony with a shortage of
queens in relation to the amount of workers. Queens from a different source colony were
used, however all of crazy ant source colonies came from a population where the ants
behave as a supercolony (Holldobler and Wilson 1990), and there was no aggression
toward the adopted queen. Most (14 of 20) fire ant source colonies were used only once
to make a colony unit, though 6 of 20 were used between 2 and 5 times. Each field-
collected crazy ant colony was used to make between 2 and 6 colony units. In 5 cases,
the same source colony was used to make two colony units for the control treatment with
the same standardization factor (500 mg workers or 1000 workers), and in one case the
same source colonies were used for 2 competing pairs of fire ants and crazy ants. We
treated these colony units and pairs as independent data points because the queen and
workers were unique for each unit and a preliminary analysis showed that the response
variables of these units were not more similar to each other than to other colony units.
Colony units were housed in 20cm x 12cm x 6cm plastic containers with a layer
OfTanglefoot around the upper edge. Each colony unit was allowed to acclimate to its
container for 2 to 14 days before the start of the experiment, during which time all colony
units continued the diet of sugar water and freezer-killed mealworms. Colony units were
then starved for 24 hours before the start of the experiment on July 3,2008, at which
point they were given access to an identical foraging tray via a 5cm-wide bridge of
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