1985] 
Sorensen, Fletcher, & Vinson — Solenopsis 
67 
transfer to virgin fire ant queens is high, we cannot rule out food 
exchange as the primary mechanism for the transfer of inhibitory 
queen pheromone in fire ant colonies. 
Our results from the second experiment also agree with the 
hypothesis that the quantity of inhibitory pheromone produced is 
positively correlated with fecundity of the mother queen (Fletcher 
and Blum, 1983). The mated queens used in this study were only 
slightly physogastric, thus evidently limiting both the amount of 
inhibitory pheromone produced and their attractiveness to workers. 
As predicted, the quantity of radioactivity removed and transferred 
to virgin queens decreased as the weight of the mated queens 
decreased. 
Summary 
Two ways in which an inhibitory queen pheromone of the ant, 
Solenopsis invicta Buren might be distributed by workers to virgin 
queens in a colony, trophallaxis and surface transport, were 
investigated. 
Using a nonvolatile radiolabeled protein in quantities iiondetecta- 
ble to the ants, evidence suggested that physical contact was an 
efficient mode of transmission for inhibitory pheromone. On the 
other hand, when radiolabeled material was incorporated into food, 
virgin queens quickly received it. A second study indicated that the 
transfer of food between workers and virgin queens increased the 
amount of surface contact and grooming and thus could aid in the 
distribution of inhibitory pheromone. This suggests that trophal- 
laxis may be an additional means of distributing queen pheromones 
in this species. 
Acknowledgements 
The authors wish to thank Tana M. Busch for her skilled techni- 
cal assistance, and Drs. Gale E. Smith and Les Greenberg for their 
critical review of this manuscript. The gamma radiation counter 
used in these studies was kindly provided by Dr. Max D. Summers. 
This manuscript was approved as TA-19658 by the Director of the 
Texas Agricultural Experiment Station. This research was sup- 
ported in part by the Texas Department of Agriculture Agreement 
IAC(82-83)0982. 
