1985] 
Sorensen, Fletcher, & Vinson — Solenopsis 
59 
by returning the cover of the nest as soon as possible. Each treat- 
ment was repeated three times, using a total of six colonies. 
Secondly, the rate at which radiolabeled albumin was distributed 
to virgin queens from the body surface of the mated queen was 
determined. The mated queen was dipped in l25 I-albumin mixed in 
phosphate buffer, taking care to avoid contamination of her 
mouthparts, and allowed to dry for 10 min before returning her to 
the colony. Samples of virgin queens were taken as before. Roughly 
1 picogram (10~ l2 gm) of radiolabeled protein adhered to each queen, 
a quantity not detectable by workers (Sorensen and Vinson 1981). 
For comparison, a virgin queen, freshly freeze-killed in dry ice with 
her wings removed, was similarly dipped to determine the rate of 
distribution of surface materials among virgin queens. Virgin 
queens inhibited by the mother queen do not themselves produce 
the inhibitory pheromone (D. J. C. Fletcher, unpublished data). To 
correlate grooming with transfer of radioactivity, we also treated 
and tested freshly killed mother queens, two dead major workers 
together, and a siliconized glass rod (approximately the same sur- 
face area of the queen). Killing prevented these from distributing the 
radiolabel themselves through contact with other workers. Each 
treatment was repeated three times using a different source colony 
each time, a total of 15 colonies. Results were analyzed by compar- 
ing slopes of the cumulative number of virgin queens labeled vs. 
time (Newman-Keuls test) (Zar 1974). Quantities of egg yolk and 
albumin found in virgin queens were compared using the Kruskal- 
Wallis ANOVA and Post hoc test. 
The role of food in pheromone transfer. 
If virgin queens were fed rapidly and frequently enough, the 
inhibitory pheromone could be passed to them by contaminated 
workers during feeding. We examined this possibility by dividing 
small plastic nests in half using a wire screen which prevented pas- 
sage of ants from one side to the other, thereby limiting contact to 
trophallaxis and antennal contact (Fletcher and Blum 1981b). After 
withholding food from the source colony for 24 h, 74 workers, 35 
larvae, 15 virgin queens, and the mated queen were removed and the 
queen together with 37 workers and the larvae placed on one side of 
the screen, the virgin queens and remaining workers on the other. 
The mated queen was then removed, dipped in l25 I-albumin and 
