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(Mirenda and Vinson 1981). There are two behaviorally discrete 
subcastes, nurses and foragers, and a third intermediate subcaste, 
reserves, that are transitional in behavior. Workers typically pro- 
gress from nursing to nest maintenance to foraging. However, they 
progress at different rates depending on size which, in turn, is corre- 
lated with longevity. 
To access the flexibility of the temporal caste system, we focused 
on tasks that were critical to the survival of the colony: the mainte- 
nance of an adequate food supply to the queen and brood. The use 
of radioiodinated protein and differentially marked subcastes 
enabled us to trace resource flow through the colony. Normally, 
foragers exclusively forage, nurses exclusively tend brood, and 
reserves mainly relay food from foragers to nurses (Mirenda and 
Vinson 1981; Sorensen et al. 1981). By selectively eliminating tem- 
poral subcastes we were able to assess the ability of the remaining 
subcastes or subcaste to alter their current response behavior to 
food and replace the missing workers. 
Materials and Methods 
Ants used in these experiments were from polygynous colonies 
collected in College Station, Texas. Laboratory maintenance 
procedures were as described previously (Sorensen and Vinson, 
1981). To separate temporal subcastes, colonies were transferred to 
behavioral distribution nests (Sorensen et al. 1981) and separated by 
their location inside and outside the nest during food presentation. 
Subcaste members were then chosen at random and marked with 
fine colored wires (Mirenda and Vinson 1979). They were placed in 
two stacked clear plastic cylinders (7 cm high, 10 cm diam., 
Sorensen and Vinson 1981) with the upper chamber as a foraging 
area and the lower chamber containing a small shell vial to serve as 
a brood chamber. Brood and queens from the mother colony were 
added and held with the workers for 24 h. Radioiodinated albumin 
mixed with egg yolk powder (Sorensen and Vinson 1981) was then 
placed in the upper foraging chamber and replenished as needed 
over 7 days. Radioactivity was measured with a Searle 1 195 gamma 
radiation counter. Workers were measured daily in gelatin capsules 
and returned to their respective containers (Sorensen et al. 1980). 
Larvae were measured together in one capsule to minimize 
handling. 
