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Psyche 
[Vol. 94 
As in the previous experiments, each group was placed in a fresh 
box with fresh nest dish. After 24 hours to recover from the move, 
all the experimental colonies, except P5A, were presented with 20 
pupae from F. nitidiventris nests. P5A was presented with 20 pupae 
from F. schaufussi nests to check for a possible order effect. After 
five days, a count of surviving pupae was made in each group and all 
pupae were removed. Following a three-day recovery period, 20 
pupae of the alternative slave species were presented to each colony. 
After five days another count was made and again three days were 
allowed for recovery. This cycle was repeated two more times, using 
15 rather than 20 pupae (due to a decreasing laboratory supply), so 
that each colony received six presentations, three of pupae from 
each species for a total of 55 pupae from each. 
Results 
All experimental colonies consumed significantly more F. nitidi- 
ventris pupae than F. schaufussi pupae, including the group con- 
taining no P. lucidus workers (Table 4), suggesting that this is 
characteristic of F. schaufussi workers, whether free-living or en- 
slaved. No correlation was found between the size of the colonies or 
the ratio of slaves to raiders and the amount of pupae consumed, 
although variability in both size and the ratio of slaves to slave- 
makers under natural conditions is much greater than that repre- 
sented here. Previous research (Goodloe et al., 1987) showed that 
a P. lucidus raid on a host species other than the one already present 
in the nest is a rare event. Cool-Kwait & Topoff (1984) estimated 
that 75% of the brood retrieved by P. lucidus raiders is consumed. 
Considering the differential consumption of pupae according to 
species shown in this experiment, it seems unlikely that any pupae of 
a slave species, other than the resident one, would survive to eclose 
in a P. lucidus nest. 
Discussion 
The first hypothesis concerning the origins of dulosis was Dar- 
win’s (1859) suggestion that slavery developed as a by-product of 
brood predation among related species. A second hypothesis (Wil- 
son, 1971; Alloway, 1980; Stuart & Alloway, 1982; Topoff et al., 
1984) focuses on territorial interactions, with opportunistic brood 
predation, as the main pathway to dulosis. Both hypotheses assume 
